Credit Card Terminals
Once in a while, you will come across credit card terminals. There are probably thousands of different models out there, and there are millions of people who have started a home business and failed. I have purchased several credit card readers, and they were all good buys. I have always paid a dollar or two, and the worst one I sold went for $20.
Obviously the newer and small the machine, the more it is worth. I sold an Omni 3750 exactly like the one pictured on the left for $37, which although is a far cry from the $125 that Amazon is asking, was still a great return on a $1 buy. For the most part, it is hard to go wrong spending a dollar on ant modern user-interactive electronics, so don't be afraid to make that gamble. You can always donate it to goodwill and take the tax write-off.
The next latest and greatest thing for processing credit cards is the wireless terminal. These sell for upwards of $500, even on ebay. I highly doubt you'll find one in a pile of junk at a garage sale, but they are certainly out there. With the economy in shambles and businesses closing their doors, there is opportunity everywhere to find deals on this sort of thing. Another trend on ebay is to sell these c.c. readers in lots of 8-10. There is only a small discount for buying these in bulk, and it is a great way to dump 10 at a time and have a nice quick auction for $500 or so.