Try before you buy: Youtube user Maddenomics
has uploaded the entire soundtrack onto her account.
Songs I like:
#2 Friends Band of Skulls
#4 Possibility Lykke Li
#5 A white demon love song The Killers
#7 I belong to you (New Moon remix) Muse
#10 Monsters Hurricane Bells
#15 New Moon (The Meadow) Alexandre Desplat
I like all of them, actually, but these are the best ones.