I've been on the lookout for some deals before; what the "best" are depend on if you count relative price or absolute price.
A few highlights:
- I got a used Playstation with copies of Lunar: Silver Star Story Complete, Vagrant Story, and a pile of other rare and valuable RPGs for $5
- I got a set of TI-89s and TI-89 Titaniums off local college classifieds for under $20 which I proceeded to resell above $60
- My primary Trumpet, worth at least $1900, I got for $1300 in near-mint condition used.
- My current Laptop - Dell Latitude D620, 1.66Ghz C2D, 2GB RAM, Warranty, the works - which I got for $500. Tough to place an actual value on it at the moment since everything fluctuates so much, but for a name-brand top-quality machine still under warranty, I consider it a steal.
I'm sure there's plenty of others I'm forgetting too.
Jam it back in, in the dark.