right now , their x39 ammo is running about 4.00 per box, for new mfgr stuff like wolf, silver bear, brown bear, etc. that is for a battle pack size, more is a little cheaper. I think their cases were about 115. per, last I checked. don't know what his milsurp is running for cost, though.
You may have been accidentally overcharged...
plus, I think he is even a few bucks cheaper, if you catch him at a gunshow.