I used a joystick (Logitech Wingman Extreme 3D, now my gear selector) for almost a year of LFS, then i brought S1 and a wheel at the same time, and the wheel after a bit of pratice did make my laptimes a lot faster. Problem with joysticks is fatigue, and trying to be consistant in the corners.
If you don't have £70 spare for a Driving Force Pro, splash out £20 and get a 2nd hand Microsoft Sidewinder force Feedback. I have a non-FF one, used it for a long time and got very fast with it. Still use its pedals (I believe they have laser pots). For a bit more you can get the Logitech Momo Racing, never used one but apparently they're nice units.