I turned my storage room into one very cheaply.
Use a saw horse as your steering wheel platform.
Set the seat and pedals into a position that matches your car by packing the chair up with wood.
Cut the saw horse legs down to match your cars steering wheel position.
I use a projector behind my head, which projects onto the whole wall.
I rarely play games anymore, but when i want to, everything is perfect and setup ready to go.