except for the post saying that moscow is expensive and the one telling about the marriage services who usually have rooms handy, the rest of the posts is ignorant bullshit.
Prices for hotel rooms and h**kers went totally out of control.
Depending on how long you want to stay, I would advise you to stay in an apartment you rent.
There are several agencies like euroapartments.ru who can rent apartments with pricings between 60 and 300 EUR a night.
One such agency is run by "moscow rick", who is an american guy. Beware of the sales pitch though.
For about 100 EUR a night you can expect to stay in a clean apartment near the center (3 or 4 metro stations away).
For better location near the center, count between 140 and 180 EUR (still much cheaper than a hotel).
An apartment is also better than a hotel, because most hotels will not let you go in your room with a h**ker, or will ask for extra money.
If you need to be near the center, there are apartments in nice streets like bolchaia nikitskaia, which is just a short walk away from the famous "nightflight" h**kers nightclub.
Warning: quality is good, service is average, and prices are steep (7000 Rub for a night, about 3000 / 4000 for 2 hours)
Another club you might want to check out is "the boarhouse"