Moscow is a real hit and miss town - either extremely expensive or bait and switch.
when I was in moscow I used this site,
http://www.rusdosug.com/ but YMWV (Your miles will vary) takes a lot of phone calls to get someone to come.
If you are staying in a hotel, there could be some WG in the Lobby bar, or if you are desperate,ask the doorman to procure. But be warned, it will be expensive.
I was also having dinner in the old jewish quarter, andthere were a lot of WG there eating (had a friend who spoke fluent russian and translated the conversation at the next table. We were speaking German)
Also according to locals, the HIV rate is really high compared to other mongering towns - lots of it goes unreported and a local with connections told me it may be as high as double the official rate.