BizMan,
So, they are getting some sort of guarantee, that's good. As far as this service goes and others like it I think that you cannot compare it directly to responses from a printed ad yet. Maybe a couple of more years from now will be much different.
I think that you have to look at what you are spending on this service just like advertising. After 2 weeks you've spent $4 in advertising. That same 2 weeks could easily cost $200 in the telephone book. So, if you get about 1/50th of the calls you're even.
Bill
