Steel Fury http://graviteam.com/games/steel-fury-kharkov1942.html
Should be cheap,plus there are lots of mods for it.

If you fancy something with a bit more 'meat' to it then....

Steel Armour Blaze of War http://www.graviteam.com/games/210.html (a steal @ £19.99)

In fact check out the Graviteam website http://www.graviteam.com/index.html

The Ukrainians seem to have the tank sim market all sewn up right now.