Automating CD lookups

I want to look up info on my out-of-control CD collection: UPC, Title, Artist, ASIN, quantities and prices at Amazon, quantities at SwapaCD and/or lala.com.

What I have: a spreadsheet with titles/artists, some UPCs, some ASINs.

So I think I need a handful of scripts:

Look up UPC (given title / artist)

Look up ASIN (given title / artist)

Look up quantities and prices at Amazon (given ASIN)

I also need a data model (which Kernigan & Ritchie say is more fundamental than code).