I haven't spent much on my new MX5 yet, but I've got a whole upgrade plan set up for the next couple of years. I'm sure I won't be one of Brian's biggest customers, but I'll have plenty of GWR stuff on the car.
Back about 10 years ago when I was single and working two jobs, I had a 97 Neon ACR coupe that I was turning into a track car. I cringe when I think about how much money I put into that little beast, and ended up never finishing. It was at least twice the original price of the car in mods.
It had a custom-built race motor with huge cams, ported heads, a custom ITB intake setup, and stand-alone engine management. Then the interior was all stripped out with a nice cage, Kirkey racing seats, Sparco steering wheel, custom instrument panel with VDO gauges, etc. It also had coilovers and upgraded swaybars.
Unfortunately, the it took the engine builder almost two years to complete the motor that was supposed to take 3 months, the cage fabricator took 9 months to do a one month job, and then I couldn't get the tuner to squeeze me in between their high-paying customers. By the time I could have gotten it all sorted out, I wasn't working the second job any more, and didn't have the money to finish it up and race it.
So it sat for a couple of years, and I ended up selling it for pennies on the dollar. But at least it was a good hobby that kept me out of trouble for a few years.
I think I only paid about $11,000 for the car new in 1997, and the motor alone ended up costing me close to $12,000 plus at least another $10,000 between the custom roll cage and all the other stuff on there. I did learn one valuable lesson, though -- if you really want a race car, buy a used one that someone else has already lost their shirt on instead of trying to build your own!