I just got back from Berlin where I picked up about 20 CDs at Flea markets for ridiculously cheap prices (between EUR 10 and some as low as EUR 1!).

Some nice stuff I would probably not have bought at full price:

Jennifer Rush - Movin'
Motorhead - March Or Die
AC/DC - '74 Jailbreak
KISS - Killers and Creatures of The Night (had the LP)
John Farnham - Chain Reaction
Grand Funk - We're An American Band
Montrose - Warner Bros. Presents
Family - BBC 1 Live In Concert
Demon - One Helluva Night

as well as a few non-rock stuff like Patti LaBelle, Blue Blot, Rupert's Kitchen (great funk band from Berlin), Flashdance, Diane Schuur and others.