I've found two inexpensive options for wi-fi in Moscow.
First, if you are staying at the Marriott Grand you can use Boungo for $9.95/day or less if you have a monthly account. Boingo connections are made through the MoscomNet access point throughout the hotel, but at a much lower rate. MoscomNet charges about $30/day!
The second way is through Golden WiFi. This is a little bit more complicated because you have to set up an account and then purchase a card to pay for the account. For about 500R you can get an account for a month. If you don't use it again within a certain amount of time it expires. In the Marriott Grand the connection works well if you are in a room overlooking Tverskaya. In other parts of the hotel you won't be able to get a Golden WiFi connection.