FFXII is no brainer for me. I have been a great admirer of Sakimoto for years now! Top priority there and it's Final Fantasy...
Ace Combat Zero The Belkan War is the second obligatory purchase for me. I'm a fan of this series and especially of the Namco Sound Team. Every Ace Combat OST is worth... twice!
Then there are the OSTs I will take a look:
Baten Kaitos II: I have the first one, I really like it. The battle is awesome and the rest of the soundtrack is really good too. Of course I'm looking forward the second installment, despite the fact I have been a little disappointed by the new battle theme heard in some videos... though there are some good samples
there.
Wild Arms The Complete thing: I cant believe they are going to release the complete NOW! So yeah Wild Arms is one of my favourite RPG soundtrack and still easily the best of the series (by far). I will closely look at the composition of each disc though. If I find out there are too many tracks on each disc, I won't buy it.
Finally I need one reprint:
Vagrant Story: I have the CD-R burned from my former original copy, but I want the original one, period!
Jam it back in, in the dark.