|Virgin Atlantic Lounge at Heathrow|
Annual memberships can be bought using money or frequent flier miles. Delta, US Airways and Alaska sell them for $450, Continental and United offer them at $475, and American has them for $500. Several of these memberships offer reciprocal admission to other airline lounges, meaning you may have a Delta membership but you have access to Alaska Board Rooms.
|United Airlines Lounge|
There are also non-airline airport club programs. Priority Pass gives you entry to 600 lounges worldwide. Memberships cost $99 annually, plus $27 a visit or $399 annually with unlimited visits. This is one of the best options because it gives you a broad range of choices, rather than limiting you to one airline lounge--plus you can check out all of them if you want and gauge which one has the best amenities. American Express Platinum Card airport club program and Diners Club cards give you access to a number of different lounges as well, but come with a few more limitations and less choices than the Priority Pass.
No matter what option you choose, you'll get a pretty decent deal out of it, especially if you find yourself at the airport on a regular basis. I know that once I start traveling more, I am definitely getting a membership to the lounges, because the few experiences I have had with them have been heavenly.