I've had some good luck over the past 3-4 years. A few of my scores are as follows:
70's Kenwood receiver - $2 at a church rummage sale - still use in my main system
Rotel Turntable - $2 at a church rummage sale - used on and off for a year, decided I didn't need another table, sold for $75
Realistic Mach Ones (series 2) - $10 at Salvation Army - after redoing the woofer surrounds for $30, I sold these for $85 after enjoying them a few months. They just took up too much space.
Acoustic Research AR-4x's - $10 at Goodwill - Used these for a year and a half in my dorm room, had to sell for $100 after realizing I didn't have the room at home.
I hated turning around most of these things, but I did enjoy them all and it came down to needing space/money more than the components. I wish I could have kept both pairs of speakers though, they sounded great for different things.
Sadly the quality of items around here has dropped off sharply. I rarely visit that many thrifts around here any more, but the main Salvation Army on my way home from work has almost no records any more and have had essentially nothing audio related for the past few months.