I pay £0.01 + £1.26 delivery from Amazon I'd pay no more than £2.50 for anything they predates 2000, 2005 even. Anything from 2005-2012 I'd maybe pay up to £4 if it's a CD I particularly want.
I use the Amazon used section, just like Tim does.
If I really want a CD, I'll pay full price for it. I've came to the conclusion that if I'm wanting CDs from the past, I may as well get them used. I've noticed that some HMV stores have started with a thing called 'swap/shop' that allows you to trade in CDs for £1 each. You can buy the used CDs for £2. Today I actually bought one: Jagged Little Pill by Alanis Morissette. I've heard it's an excellent album.
But to answer your question, I'd echo what Dan said.
^ Will do. I'm very curious as to what it's like. Given it's a real Nick Rhodes-driven album, I bet I'll love it - he and Trent Reznor are the reason I got into synths, self-production and keyboards.
I should clarify the Jack White album is currently being bid on for 99 cents total from Hong Kong. No matter the price or where it is, as long as it's rippable and in English.