Its not really that hard.

All you have to do is go down to the steel yard and pick up some square tube aluminum (or steel if you want weight to it).

Measure out your lengths in 2x2 square tubing.

Then make cross braces out of 1x1 square tubing and have it tig welded together making your base frame.

From there you place 2 cross braces for your seat mount out of some flat strap metal. Drill your holes for your seat and mount it.

Then measure your foot placement with the controler pedal height compensated on it as well as height etc. Cut a piece of 2x2 and weld it to one of the cross braces and mount your pedals on a platform and secure it.

Then measure out for your steering wheel and angle cut a piece of tube for that including a platform to mount the wheel to.

Weld it all up and poof you have a gaming seat for probably less than $100 (if you have a spare seat around, and you know someone with a welder).

Now I know not everyone directly knows someone with a welder but I am sure everyone knows someone who knows someone who has one and can work out a deal to get it done either real cheap or for the parts to make another or whatever.