Another thing we might want to keep in mind here...

I get quoted for x amount of BTC, and I have until 6 p.m. to deposit the money.

At 4:30, I go, deposit the money while I'm running various errands. I get home at 7 to find that my order has been released to someone else because I didn't provide proof of purchase in the allotted time frame. Now I have no BTC and no way to get a refund. In addition, the seller got a double deposit - what then?

All of this is purely theoretical, and food for thought.