Pedals, steering wheel, etc...?

I dumb most of my "fun" money into my Karts, which can be very expensive. I don't want to dump a ton of money into a set up, but where is the "sweet spot" as far as the gear goes? Ive heard some will use their old kart chassis and seat and cut it up so that is the seat they use and have everything mounted as if it matches (somewhat) our kart set up. I don't have any spare chassis around any longer, so I might be needing to get the whole set up.