Get a free $2 MP3 credit in the Amazon MP3 store using the coupon code STUDYBRK. You can enter the code on any MP3 product page, or use this handy page. Note that you can get one credit per account/customers and must use this credit by November 28 (the credits you can get from delayed shipping shouldn't expire until the end of January; Amazon automatically uses credits with closest expiration date first, so you don't have to worry about managing them, though).
When you get a few credits stored up, be sure to check out the 100 Holiday Albums for $5 each sale or the Black Friday Deals Week sale - it looks like I already have enough to get the one album (I'm considering the Mannheim Steamroller Christmas 25th Anniversary Collection).
For those searching for free music, be sure to check out my weekly legally free music post which this week included Lights Vol 2 A Hanukkah Sampler.