Without giving away ALL my sekrits...
1) Best deals recently - Bittco Super Vemar 135mm f3.5 LTM (it is *really* a Kyoei Acall. I only knew that because I know what the Kyoei looks like, and recognized it.)
2) Another Arco Tele-Colinar 135mm f3.8 LTM ($1.20 folks. Really).
I look for words spelled incorrectly, or in the wrong category. I have had some limited success with taking apart lenses and bodies and doing some minor repairs, so when the seller is honest and says that a lens is hazy or a camera body doesn't work, that's often an opportunity. But it is also a crap-shoot because sometimes haze is between elements that are cemented together, and sometimes physical damage to a camera is more than I can deal with (my abilities are pretty basic).
Some cameras I pass by because I already have one or more examples of them, and no matter how good they are, no matter how cheap they are, nobody seems to want them and they don't get sold. I try to make myself not be the 'bidder of last resort' on stuff like that. Minolta Hi-Matics are like that. Honestly, I don't know why no one wants them.
Best Regards,
Bill Mattocks