you'll hear from multiple members that they're probably stolen. A keg costs upwards of $100 each, used, so the deposit people put down is just that, a deposit. To get beyond that, the deposit is $30 each, so yes, $25 a pop is a deal. What frequently happens is the store where you got the keg from might not accept it back for your deposit return after a certain amount of time, which is stupid cause the brewer still wants it back. But that's how it happens sometimes and this guy might just be trying to get his money back.
If there are any micro breweries in your area, call/contact the sales guy or owner and see if they have any damaged or with different couplers that they can't use. That worked for me. Got some cool older kegs.