Airfare

Nobody has a crystal ball in which to make predictions.

Look at websites like sky scanner and Google flights to see what’s out there.

Most importantly, buy directly from the airline and not from a third-party because if flights are canceled or there are delays in which you missed the connection, you’ll have to reach that third-party wherever you are to help you.

No, that's not a great fare, but Prague is not a very large gateway city like Munich or Frankfurt (see what it would cost to do round trip to Munich for comparison's sake). Fares will go up and down over time (even multiple times a day), so track over several months since you have the benefit of time. You don't have to feel rushed to buy anything right now. If there's any way you can fly out of LAX, the fares would likely be more competitive.

You will have to be flexible with exact dates, airports, carriers, and routing to get the best fare. I wouldn't write off third parties like Expedia but know the drawbacks (the more complicated the itinerary, there is an increased chance of not everything proceeding smoothly).

The airfare right now is $1500.00 per person

Is that round-trip, or each way? Is that minimal stops with reasonable, convenient layovers, or some horrible routing that goes crazy with multiple long layovers? In a decent seat, or in Misery Class? If each way (and other negative factors), that's super-expensive. If round-trip....might not be awful, but you may be able to do better. You are going in "shoulder season" (outside peak summer travel when fares tend to be highest) so that should help a little; on the other hand, airlines reduce flights outside peak season, so you may have fewer options. But as stated above, there's no crystal ball.

You're flying between Phoenix and two cities that don't have tons of competition (Munich and Prague). You should look around, consider exactly what you're getting (all the details - don't just shop exclusively on price, or you may regret any "bargain"), and above all be flexible on dates/times, and other variables. It's worth investing some of your time.

Condor Air has flights starting at $887, but for dates a day of two earlier or later. (flight duration about 15 hours, including layovers)

Try: http://matrix.itasoftware.com/

Use the multi-city tab. You can screen out the excessively long flights but using the 'Duration' drop-down column header on the resulting list of flights.

To piggyback on what David said . . . I recently purchased tickets for an August trip. One thing you need to be VERY careful about is the details of what you are buying. Many airlines have introduced a super misery class, which goes by various names like “basic economy.” You’ll know if that’s what you’re considering if somewhere along the purchasing process you are told you will be assigned a seat during check-in (think middle) and that you are allowed carry-on only; i.e., no checked bags. Some people are fine with that. Not I. I can’t imagine enduring anything worse than we already experience in regular economy.
Unless the fare were substantially lower, like $300 or$400 for using a different airport, you need to factor in the cost to get to and from where you really want to go, possible extra hotel nights, and inconvenience.
You are far enough out from your trip that I advise setting up a google flight alert. I think you can do it on skyscanner, too. Be vigilant about those “basic” fare offerings. What someone said about constant price changes is absolutely true. I started monitoring prices daily and saw $400 differences in a day or even within hours. If after some time of checking, $1500 seems like the going rate, you will know when a better deal appears and can grab it.

Meredith. My wife and I have been travelling to Europe regularly for 15 years or more. We've made all the travel mistakes possible. We just returned from 5 weeks in England, Germany, Greece and southern Italy. No doubt you will get a lot of good advice about travel planning but these are the things we've learned. We too fly out of Phoenix...not the most convenient home base.
1. Cheap is cheap for a reason. We all love to snag that great rate. The flight from PHX to LHR is 11 hours. We are not kids anymore, and sitting in basic economy can be pure torture...no sleep, aches and pains etc. Our Europe side recovery time was substantial. We used to fly to another hub and grab the least expensive transatlantic flights but our experience here was that the all-in costs, delay risks, total transit times and associated connection difficulties just were not worth it. We now fly direct to London (LHR) round trip and jump to our target location in London. This year it was a 2-hour layover in London, stretch our legs, grab a coffee and off to Munich. Jumper flights on BA from LHR are extraordinarily inexpensive, LHR allows you to defer customs until you reach your destination. If for some reason a connection is missed, there are usually lots more available. We learned to travel without checked luggage (light) on these long haul flights and thus eliminate the need to pass through customs, collect bags, re-enter security and drag bags to you new terminal (it's always at the other end of the airport. When you add up total air travel costs and apply a value to your vacation time it's an easy choice.
2. Buy your air tickets as early as possible. Ignore all the great charts showing the cheapest days to buy etc. We select aisle/window when we travel Preferred Economy or aisles across otherwise.
3. Set your VPN to identify your computer as operating in the target currency. Make the purchase in local currency and convert at best rates. Make certain you use a "No Fee" credit card. I know this sounds goofy, but, I just bought round trip flights to Toronto direct from PHX non-stop. Setting my VPN to ID Vancouver, Air Canada quoted the rate in Canadian Dollars assuming I was a Canadian travelling. When I received the same quote with a PHX Id ( no VPN shield) the US price quoted was substantially higher than the US converted Canadian Dollar price. In this case, AC knows they have a virtual lock on direct to Toronto flights and charge US buyers accordingly. BTW, never let any company convert their charges to US currency. They know they can add substantial conversion and interest fees. It works more often than not.
4. Set layover times for European Connecting flights longer than you think you need. You may not need it, but when you do you will thank your stars.

Good luck

Did you check fares on kayak.com or matrix air?

The fare seems a bit high, but not outrageously high.