Here's somewhere to start:
http://www.amazon.com/Disneys-Happiest-Celebration-Earth-Disney/dp/B00092ZLKI/ref=pd_sim_m_8
Start there, and then see where
Amazon leads you. Look around on the pages, and there are other CDs listed, too - go all the way to the bottom.
This one is even better, but they want $90 for it:
http://www.amazon.com/Official-Disn...=sr_1_2?ie=UTF8&s=music&qid=1253463303&sr=1-2
We have an official Illuminations CD, a Finding Nemo Musical CD, an Animal Kingdom music CD, a Candlelight Processional CD, a Wishes CD, a Spectromagic CD, a Magic Kingdom Event Party CD, a CD of parade music called "Magic in the Streets". I know there is also a Festival of the Lion King CD. I see some of these on Amazon, so just search around on there. Or look at the CDs when you are actually at WDW.
It's not just park music, but if you don't have this 5-cd set (there's also one that only has volumes 1-3, but look for the 5-cd set), I highly recommend it for all Disney fans. They used to have it cheaper at Borders stores, but I don't know if they will still have it. I don't see it on their website, but if you have a Borders you might go look in person:
http://www.amazon.com/Classic-Disney/dp/B000FHYYAK/ref=pd_sim_m_48
Also, go to
www.live365.com. They aren't CDs, but there are tons of sites that play Disney park music, including tons of background music that is not available to buy on CD.