Not really a garage sale find, but it still qualifies as a great find in my book.
A Pentax M 120mm f2.8 lens for 120 Aussie dollars - and it's in pristine condition. These things seem to be rarer than rocking horse poo, I can't find that much info about them on the net. Looks like a perfect companion to my 100mm.
I love the M series lenses, the build quality is fantastic.