Massdrop version are directly from manufacturer or authorized vendors, never from gray market.
With that said, I'd like to relay a negative experience with one of these... Bought one retail last year, from a Verizon store. Paid like $60 for it. I was in a hurry and I don't have time to go hunt for a cheaper one (wasn't for me, I use a LG Tone+) Careful with the flip out mic. If it breaks, it's game over. And yes, that's what happened to mine. Can't get it to turn on any more, even though otherwise there were no damage, but that little flip-out mic "switch" is toast.
At $24, this is a good price for a name brand BT headset, when you see generic BT from China for $20-30 claiming 4.0 or 4.1 BT and other blah blah blah.