Yep I know. The one you get for 2.6K are unmarked D43. They can be fake. And also no official warranty on them.
The pricing is as follows for hynix(512MB CHIP).
Duplicate D43: 2-2.2K
Unmarked D43: 2.5-2.6K.
Marked 100% genuine Hynix D43 : 2.75-2.85K.
The one which i got are 100% genuine marked Hynix D43. And yes they usually do 280 without any trouble if you have voltage to provide.
You get what you pay for.
I bought them only after testing them to make sure these are original Hynix and not fake. the guy i knew allowed me to test before i pay him as he was 100% confident theatthese were original. So spending Rs.200 more is totally justified if you ask me. He wont cheat on me, he is my old friend. Used to work under me once
Has agreed to replace them anytime under warranty.