Good rule to follow, Take the number you think it's going to cost you to build and tripple it. By the time you add up all the hardware, tuning, and jewelry for the wife. If you think it'll cost 5k, it'll probably be 10-15k by the time your hair stops falling out. That being said, i'm quite happy with the power my s50 with the vortech s/c.
2012 vw golf: DD
1974 vw camper: most fun possible with 50hp
1998 Jeep tj: topless and dirty
1991 318is s/c: dirtE30 - sold