To clarify, client owes me $273. It's easy to confuse: he paid $150 deposit and offered additional $150 for the orig files. I'm asking for additional $273.
If he's this angry, he's either a prick, or he's a prick who really needs the original files. Nonetheless, just stay on the course. If he really needs it, he'll pay you for it. you've got the winning card, now work on your poker face.