it depends of the service you're using, for example, getafreelancer has its own escrow service but you can use hxxp://w3.esc*r0w.com/, it's used when trading cars, sites and other stuff.
cheers
http://www.alstrasoft.com/escrow.htm
look at all altrasoft reviews first i was looking into the exact same thing and most of altrasoft software are very buggy.....not to many satisfied customers
Why don't you get a programmer to do it for you? I would help you out but right now I'm booked with several projects.
It shouldn't be too hard to make such script, but I would recommend you to heavily test it before using, you now... there is money to be stolen...
You Planning a escrow service ? EScrow. c0m
Well yeah i can see your point Most escrow services are for big ticked items like cars and boats or anything over $50 like you said , but i have a little twist on my idea lol Are you a webmaster therookie?