Loving it

Had a nasty surprise when ramping my car at work, a small hole in the sill turned out to be a gapeing chasm!! I'm in the fortunate position of teaching mechanics at college though and my friend who teaches the welding course (best I've ever seen) has kindly offered to rectify it he's about half way through at mo and it will be mint , strong and look perfect when finished. Its a 90 tt manual with 426 bhp few nice mods and shows 64k with some paperwork to make me believe it's genuine, it's a uk car as well in white. Turns heads like nothing iv been in and goes like poo off a shovel. It confuses me a little why 300's are worth so little, supras 10k ish,skylines the same , z's just seem so cheap similar price to mr2s and things leagues below ,I was only planning on keeping it for summer 4 or 5 months but not sure now. Does anyone have an opinion on if they think the values will rise on these or are they always gonna be the performance bargain. I payed 3700 for mine and although not mint (couple small scabs n marks here and there) I'd describe as excellent for age . It would take n offer over 5k to even consider getting rid and even then there's nothing for that money that does what this does