Yara, ask the guy if it's real or not. If, after buying, you find out that it was a fake, go shoot the guy. Next time, no one will lie to you in business. At least, that's how we take care of business. Religion (conscience) and business (money) are two very different things, never let one thing cloud your judgement. If someone cheats you out of money. Kill him, or at the very least break both of his legs and hands and be sure he can't speak ever again - you're an intelligent guy, so I'm sure you don't need instructions on chemicals!
Price no idea. Yara, I bought most of my weapons ages ago. I mean literally long long way back. Other than two M4's. Them too, I got smuggled (kind of)..... so no idea about street prices there nowadays.
Shove that pratha up your......