Is it ever worth buying Euros ahead of time?

What you are trying to engage in is currency speculation. Even the pros have trouble forecasting the direction. Your example assumes a 33% swing in value which is most unusual and unlikely in the time frame you have. Ok -- lets look at real numbers. It is very unlikely that you could obtain currency in the US at less than a 5% mark up. The AE office in Denver charges between 8 and 10%. It is reported that WFargo charges 5%. Now the money you converted to Euro could have earned another 1 or 2% in a saving account. For you to just break even you need a swing of at least 7% or maybe more. Now look at historical data and see if there has been a 7% swing in six months -- how many? What if the value flattens out or declines a bit -- then you are really behind. You (nor do I) do not have the ability or knowledge to play the currency speculation game. Save money else where in your travel budget.

Maryam,
I think it is a terrific idea to buy euro when when they are at their lowest. There is a problem with the execution of the idea, when is the euro at the low. If you want to speculate this might help http://www.fxcm.com/forecast-eur-usd.jsp?CMP=SFS-701300000003XGdAAM&keyword=Currency_Forecast

I agree with Frank. Not only do you have to guess which direction the euro is going to move you must be right by more than 7%.

This is one of those questions that can only be answered personally. That is, what works for you and is most comfortable for you. I live in a town with an American Express exchange bank, so I get all of my Euros before I leave at a minimal charge.

Some people would cringe at that idea, but it works for me in one particular way: I then budget my trip based on the Euro, not on dollars and the current exchange rate. I do take a credit card and some dollars in cash, just in case.

I am not uncomfortable carrying all my cash in a money belt, but some people would just never do that. I figure, if I don't tell anyone or show it to anyone, who's to know?

So, my reasons for the way I handle exchanging money seem to be different than yours. I don't want the hassle of exchanging money overseas, and I want to budget based on the Euro, not on dollars. That is why I do it my way.

I hope this gives you some food for thought. But, again, it comes down to what makes you comfortable.

I take a little bit of money, just so that I can have some upon landing to get me to my hotel and to get me a meal. The last thing I want to worry about after a transatlantic flight is to have to run and find an ATM with all my luggage, jetlagged and excited to get going on my trip. But I don't think I'd ever want to bring ALL of my cash with me. It'd freak me out personally to carry that much cash. I also like charging as much as possible. I'm used to paying that way and especially bigger expenses like hotels, nicer meals, and nice souvenir purchases, I want to keep track of those using my CapitalOne card (plus with no fees and 1% cash back on all purchases, it's a great deal).
Basically Maryam, you're asking about whether it's a good investment to buy a lot of Euros when the rate's low. As the first reply said, only you can decide. I'd feel uncomfortable just keeping that amount of money in my home for long periods of time, I never keep that much cash USD around and always feel like I need to deposit some in the bank if I get a sizable amount of cash. and who knows what the currency rates will do by the time you are ready to travel; they may not get much worse in which case you paid higher rates getting them here then your ATM card, which you already said gives you a pretty good deal. If you are lucky enough to go once a year or almost that often then it may be a better idea than someone like me who isn't in a financial position right now to go that often. The exchange rates themselves are never very good stateside, and I believe that the more you buy, the less fees you pay (some banks are like $8 an order, which has a lot less impact if you're buying thousands of Euros), so again only you can decide if it'd be the best solution for you.

I'm a no unless you have an immediate need for a larger amount in cash than you can draw in one day from a cash machine when you arrive.

We have usually bought some euros ahead of time just so we will not have to mess with an ATM right away. Also the last two years we have gone straight to our rented villa and they expect the entire rent in cash on the first day. We could not get that much from an ATM.
Recently I have noticed more and more posts about people having problems with their ATM cards. I have made a point of getting a second account so we will have two ATM options but it would sure would crimp one's style to arrive for a three week vacation and discover that you couldn't get any money.
Two years ago we had our ATM card eaten by a bank machine in Amboise. Luckily they were able to retrieve it for us though it took several hours (had to wait for the technician).
I do know it is important to let your bank know where you will be because they are much more vigilant regarding fraud.
All this being said it sure would be nice to know when to buy! Wish I would have bought back in May!

For my first trip years ago, I bought some but not much money prior to leaving. The next year I took just enough to get by on the first day. Since then I only take whatever is left from the last trip. I've found ATMs are plentiful in the airports and I don't find luggage a hassle since I just have a carry on. I agree with Frank that there's a lot of speculation involved in purchasing ahead as well as the bank fees involved. I also don't like to carry such large amounts of cash even though I always use my money belt. I'm sure that you know about oanda.com which tracks foreign currency rates. This is what I use to budget and can have a pretty accurate idea of what my trip will cost prior to leaving.

The only bank in the USA that I know of that sells Euros cheap -- they promise no more than a one percent markup over the interbank rate -- is EverBank. However, they do not deal in cash. They hold the Euros in an account for you at the bank (FDIC insured). To withdraw cash, you have to have a Euro account at a European bank. (They will wire the money free to Europe on request.)

This is basically a service not for travelers, but for people interested in foreign currency investing.

Xetrade in Canada is similar. They sell you Euros and then send them to your European account using EFT. Their rates are about three percent over the interbank rate.

It is possible to open a non-resident Euro account at some places in Europe. Mine is with Citibank in Spain. It includes a Euro debit card that you can use for purchases, as well as ATM withdrawals. Most ATM withdrawals are free in the Euro Zone.

I like this arrangement, but it's obviously a little complicated to set up, and not for everyone. Theoretically, if you buy Euros at the right time, it could save you money. And, the debit card is nice because you can use it anywhere -- even in USA.