I am looking for a room in Moscow.

Well, that's obvious, I'm looking for a room within a budget of 7,000 rubles.

Then buy from "Iz Ruk v Ruki" (a classifieds website). If you have the money, I don't think there will be any major problems. The main thing is that it fits your budget and the landlords are decent. And the neighbors, if there are any. I wouldn't recommend sleeping districts or the very center.