That's an interesting question. How did you come up with that idea and why exactly would you like to buy it, if it existed?
If it really exists and the price is lower than normal, P2P wallet transfer is supported, and can exchange it for cash in my country
Interesting idea. It makes you wonder why no one's thought of it before. Oh wait! This basically sounds like money laundering, which is illegal pretty much everywhere.
You could maybe offer these services on some darknet markets... but good luck with that.
By the way, most of us here don't believe in the concept of "dirty" coins when it comes to Bitcoin.