I use Amazon a lot, and ABE all the time. Now I've found
bananas.co.uk - the clearance page for The Book People - and bought 18 new books for £19 including postage. Not quite as good as Cynical Ben, and it takes some effort to find the good stuff amongst the mainstream dross, but it's still excellent.
Damn - and now I've just bought all three of
Marilynne Robinson's books from Amazon:
Home,
Housekeeping and
Gilead. Wonder when I'll reach the point of owning more books than I can read in the course of my lifetime?