Hmm, you're right - that doesn't look like the right picture, it's obviously zinc plated and the auction is for stainless. But I've bought socket head bolts from those folks before, and all of the longer M3 ones have only partial threading. I'll email them and ask.
Edit: Yep, that's a dead end, all their M3 bolts are fully threaded.
Edit: Yep, that's a dead end, all their M3 bolts are fully threaded.