I guess I am a sick individual, because I keep spreadsheets of my expenses.
Almost $15,000 in my Ford Ranger cab truck. It doesn't look like it though. It started out as 85 FS Bronco I paid $2,700 for back in the fall of 2000. I then started the cab truck build in December of 2004. It has a lot of good parts (5.0 HO, C6, Atlas 4spd, D60 HP with Reid Knuckles, 35 spine Superior shafts, 14 bolt, 4.88 gears, lockers, 42" TSL's), but needed better execution of them. It has been parked for about three years or so now. I sold the tires and wheels off of it before putting it in storage. My plan is to buy a YJ next spring with a blown motor/tranny, and swap the entire drivetrain from the cab truck into the Jeep and link it with full hydro steering.
A little over $5,500 in my Samurai. That includes buying two sets of chromo shafts for the front. I bought it stock in the spring of 2005 for $800. It has been the best bang for the buck and the most fun to wheel by far. I've got most of the parts now in storage to link it on Yota axles.