You know, I'm sure the price of an 'exclusive mistress' is all over the map...
Personally, I'd rather make $3000 a month seeing the same guy once a week then $6000 a month seeing all sorts of guys, and I know their are a lot of gentlemen who would prefer to know their mistress wasn't seeing all sorts of guys along with him. The reasons for which begin with STD's and expand to psychological issues...
I don't need a man to make me rich, just to pay for things like my rent and ballet lessons while I plan my future and work on the things that will eventually make me some REAL money...
I think if two people have an understanding and they can set their boundaries up front, it can be a great arrangement, but you couldn't pay me enough money to devote myself to someone I couldn't stand. So, basically, chemistry is everything.