This happened to me all the time when I was looking for a server colocation facility, except the phrasing was slightly different - "what's your budget?"
That's why I, in all honesty, consider prostitution a more respectable occupation than telemarketing - in the former case, both parties engage in voluntary trade and leave happy. In the latter, one party preys on unwilling and gullible, trying to take their money while giving them suboptimal-to-useless crap.
What about auctions? Or lunch trades among school children? I believe that in both of those it is common for the seller to ask the buyer to make the first price offer.
I'm vaguely aware of one single other place this happens: street-walker prostitutes. The parallel is pretty solid, actually.