K3 reputation

Sorry to bother you guys, but I have a question. I'm on the server Icecrown and I was buying with my engineering char the parts needed for the chopper. There was a guy that told me he was able to buy the parts for 750 gold, and not 1k (talking about piston). He wasn't the first guy telling me that and also in the ah sometimes I saw ppl selling the pistons way lower than their "normal" selling budget. So I wanted to understand, there is some kind of rep needed to get this discount from Roxy (the NPC that sells these items)in K3? I did some quest in K3 (I did also all the ones of sons of hodir)and nothing changed on the item prices. Do the engineer need be goblin and not gnome?

I really can't understand. Thanks for the help.

Roxi Ramrocket does not belong to any faction so I don't think it's possible to get a faction discount.

Many ppl said they do (also if none of them wants to explain how), so Idk how they actually do it, is not just one of them, but different ppl.