How does a MQ work?

[dmorawski]

The OP is asking about general conventions/protocols for payment to the MQ seller, rather than MQ mechanics themselves (though your post was quite nice in explaining that!).

I'd ask the seller how they'd like to handle payment, but I don't think a "half now, half later" arrangement is out of the question. I'm assuming you'll be dealing with people who have good reputations/reputations they'd like to preserve, so it's probably nothing you should worry about (unless something's rubbing you the wrong way). GMs don't mess with MQs, so I guess you're on your own if anything goes awry.