This has just happened to me in FM13.
At Rangers, everything was fine. Going well. A good squad of players who's valued all between £5.5m and and £2m. After the 18-19 season, we got taken over and everything blew. Club value rose to £115m, the ST price was £1,089 or something, players who were on late £20k's for wages had shot up to £45k, all of a sudden everything was inflated. I couldn't negotiate new contracts with players because, even as 22 year old regens, they were asking for £66k and what not. It was very difficult to sign players as all the values were inflated. Even my players values shot to £10m and the like. I sold a few players for £7m+.
I just closed the game down and restarted it to get the update and when it came back on everything was back to normal. Club finances, ST price down to £650, Lee Wallace who's wage was £35,000 10 minutes ago is now £22,000 and so on. Players I sold for £9m are now showing as £5.5m and such, wage budget has fell by £200k.
Completely weird. What could this be, is it a bug?