Practice, practice, practice.
Wait. I'm sorry. That's the cheapest way to get to Carnegie Hall.
Actually, though, if airfare really is an insane $2,500, take the Queen Mary 2 across for probably $1,300 each way per person counting everything. (Advertised prices are lower, but there's all sorts of tipping and stuff.) You might need to get a tuxedo.
Oh, or if you wait until the right time of year, the cruise ships all migrate back and forth and give insanely cheap prices to put people on the boat. In April they migrate to Europe and in October they migrate from Europe.
For example, here's nice cruise ship that will get you from Fort Lauderdale to Barcelona for a base price of $399 per person. With the taxes and tips and stuff it'll probably end up being $600 to $700 per person, but it's still cheap:
http://www.vacationstogo.com/fastdeal.cfm?deal=10183
Unless you stay until October you can't get the same cheap deal coming back, but the Queen Mary 2 goes back and forth every couple of weeks so you could do that or pay the high airfare only one direction.