Oh yes, there are bargains to be had - that is very true. It's spotting the bargains that's the hard part. I picked up a 2 volume set of books:
Stellar Astronomy (by Hong-yee Chiu) first edition, 1969 for US $12 + shipping earlier this year. A veritable bargain. Right now I'm seeing this book on Amazon going 2nd hand for US $20:
http://www.amazon.com/Stellar-Astron...6126122&sr=1-8
but at the time I got this book off EBay, there was 2 going and the cheapest was US $100...
Dave