A quick google brought up a few hits, most have similar figures so I assume he is in the 50-65K range.
Telegraph in mid June
"N’Zogbia’s wage demands of £60,000-a-week have forced many suitors to wait to see if a stalemate forces him to lower those demands, but Villa, keen for a big signing to appease fans following the sale of Downing and Ashley Young to Manchester United, are at least willing to get close to that figure."
Express a couple of weeks later
"Aston Villa chairman Randy Lerner is prepared to meet Charles N’Zogbia’s wage demands of around £65,000 a week."