Fishy, yes. But outright criminal? I don't think so.

Just a deluded person who thinks they hit jackpot when they found this suitcase (looks like a guitar case btw) full of "collector" phones. Probably has some hazy notion that they're all protoypes or "limited edition".

Unfortunately sellers like this, you just have to wait them out. Try again in a month or so.
By contacting him so soon and appearing so eager you just gave him the impression that he's on the right track.

Or be willing to buy the whole bunch, and prepare for some hard haggling.
But even so, you'd have to wait until he realises that he probably won't get a better offer, and it's too soon for that.