I kind of understand it from Planet Destinys Xur post. It's more for the fact that, now that we can get allegiance with a faction, they have it so you can effectively 'pay' for faction rep via heavy ammo synths as an option. Guess they wanted to put a chokehold on that.... Still sucks though.

Well it's simple bro. He buys from his supplier then marks it up. Well he kinda forgot the first rule of "not to use what you sell" and he's picked up a nasty habit lately. So in turn he has to Jack up our price to supply his own "exotic" habit. I've tried to tell him to seek out "exotic" treatment facilities but he wouldn't listen. Now he's keeping the goods and selling "NLB" aka dirt and a big mark up on heavy to supply his own "exotic" fix. Hope this answers the reasons bro. :D have a great day! :D