the single most expensive modification to my Supra used to be my Mint Speed titanium strut bar. it is # 3 out of what was supposed to be a production run of 150 units, but if demand doesn't keep up, production may get capped at 50 units. of the gazillions of different strut bars made for the JZA80 Supra, this and an HKS model are the only two made entirely of titanium. so the material and the rarity are what makes it expensive. is it worth what i paid for it in terms of pure performance gain? LOL no ...it was more of an impulse buy on a novelty item than it was a serious investment in performance...
then i bought a JIC 505S full titanium cat-back exhaust, which weighs just under 11-lbs in its entirety, and includes all the piping you can see in the picture up to the downpipe flange:
...nowadays, the most expensive modification to the Supra are my Volk TE37 wheels (19 x 9.5 F, 19 x 10.5 R, +22). they have the Seibon Edition paint scheme, which is nice and goes with my paint color well...but ideally i want to repaint them in Volk Bronze:
EDIT - didn't think about paint, which was expensive as hell to get done flawlessly even though its an OE color...