I think UrlUrl brought up a really GREAT, and important, point. If this is the result of someone attempting to "sell" domains they do not own (or have specific rights to broker) that they see advertised for a specific price on forums etc, then turn around and buy the domain quickly once they have a buyer on the line, despite the possible "happy ending" in this particular situation it points at yet another growing cancer within domaining. And, if this IS what is happening, and they are doing it at the magnitude that this annoying "Alex" guy (who keep repeatedly offering me the "opportunity" to secure expiring +S or hyphenated versions of domains I have) is spamming lately, it could REALLY be a problem affecting a lot of domains/domainers and potential endusers that get sick and tired of so many "offer" emails that they also ignore the legitimate ones.
If this "broker" turns out NOT to be the person you had given the job to then I sure would be interested in finding out who the joker is if possible.
If this email WAS from the guy you hired then, if I were you, I would really be wanting to see a change in his brokering tactics.... the email was not personalized at all (associates your domain with spam), he did NOT indicate that he was the "broker" (but rather gave the impression that HE owned the domain in question) and apparently made a considerable markup over what you were hoping to get for the domain. Sure, a markup to have some wiggle room in negotiations is one thing, but marking it up to the point where a sale/response is unlikely is another. And, I would also be concerned about the transparency of sale price/commission.... maybe you have already closed some deals with this guy in the past so is not an issue, but if it was a first time brokerage attempt and he is attempting to sell considerably higher than your expected price, I would certainly want to know how "his share" would be calculated to avoid him just pocketing the extra if a sale that much higher did go through.... but on that note, if the guy you hired can confirm/PROVE that he initated contact with this potential buyer then in my opinion he would be entitled to whatever commission you had agreed on if you do finalize a sale.
anywho, thanks for sharing the interesting story, hope it ends in a sale and that the broker mystery is solved.....