I've had oodles of terrific thrift finds over the years. Some of the ones I remember most fondly:
$3 for a Jim Thompson Thai Silk muumuu -- sold it for $375.
$6 for a long Pucci dress; next to it on the rack was a long vintage Diane von Furstenberg dress for $4. Got somewhere around $400 for them.
50 cents for a Zandra Rhodes dress, sold for $125.
Good jewelry is tough to find around here, but in the past few months I've found Stephen Dweck earrings for a dollar, and a Miriam Haskell baroque pearl necklace for $2.
I've never found any clothing that has been from a really large name designer brand. I have seen a few designer purses but I've never purchased them, because knowing my luck they would be fake.