You don't say how far in the future the wedding is or how soon you want the Euros, but I would guess it isn't today. That is why your bank can't give you an exchange rate or cost of the Euros you want to buy: they deal in the present, they are not speculating about the future (nor are they allowed to for foreign currency exchange for their customers).
The only non-expensive way to get Euros in the US is to have a friend or relative bring some back from Europe if they are visiting there and you pay them the current exchange rate for them.
Also, it is important to remember that if you are needing to take more than $10,000 worth of currency, the total you have with you has to be declared when leaving the US. If you don't , you can be detained and all the cash confiscated. You will need to carry the transaction receipts with you if you get the Euros in the US to prove it is your money.
Currency exchanges, like the ones you see at airports, are the worst place to get money because of their fees and rates. Also, they don't have very large amounts at any one time. You also don't want to take US$ to Europe and attempt to exchange there. The rate is even worse and it may take several visits to the exchange booths to get the total amount you need. Banks in Europe will not help you unless ou have an account with them. And they really don't like dealing with cash anyway because almost everything is done by bank transfer.
You can get cash from your bank. That would probably provide the best rate overall and lowest cost if you absolutely have to have cash. AAA does offer small amounts of Euros at a high cost (think envelopes of €100 in small bills) that are designed to give you enough money to buy a coffee and maybe a taxi ride on arrival in Europe. American Express sells most foreign currencies and will deliver what you order directly to your home, but they are also expensive relatively speaking.
The best route if you can only deal in cash is to find a bank that has a no fee ATM card with a high daily withdrawal limit and then use a bank operated ATM with no fees charged once you get to Europe to get the cash you need. Of course, with the average cost of a wedding, this may be impractical as it would probably take several days withdrawals get enough. Because of this, I would go with the suggestion of others to use Transfer Wise as an affordable and trusty way to get the money to the right people.