What parts are you referring to? These parts are not cheap, we have a Brand New 08 IS250 RWD with the following equiptment: 19" F-Sport Wheels, F-Sport Brake Upgrade, F-Sport suspension, F-Sport Cold Air Intake, F-Sport Chassis Brace, F-Sport Dual Cat Back Exhaust, and it totalled out to over $12,000 in upgrades !!!
12k! That makes the decision to buy an IS F seem like a no-brainer. If I was you Andy, I would grab any potential buyer sniffing around that 250 you mentioned and force them to test drive the F. Sign the papers when you get back!
it makes absolutely no sense to spend that kind of money on an ISx50. for that addtional money, the car still has sluggish autotrany and V6 power. one could easily buy an ISF that includes most if not all the F accessories. and keep in mind that a modified car may actually hurt resale value if one does not find the right buyers in the right market segment.
F Sport parts carry something unique that some other aftermarket items don't...a factory backed warranty if installed at time of purchase of course. I've driven several full F-Sport spec'd IS250's and IS350's...the parts work very well together as a nice package.