Actually i was wondering,that is it possible to buy G25 shifter seperatly?,and how much would it cost,cause i dont have enaugh money to buy whole g25 kit

Not really - you'd need to interface it with your own USB controller, as it normally just plugs into the G25.

Have you tried getting an ACTLabs shifter - they are a standalone item, but a bit like hens' teeth.

no way,cause act labs shifter is too expensive for me

Unless you know your way around the circuit boards of USB modules, then I think this way is a "no way" too.

Get a joystick and build it yourself? Look around I found a couple of programs and tutorials to turn Joysticks into shifters. Some for FFB joysticks and some without FFB. Just look around.