What is good but cheap performance for an 08 TC

Things like aftermarket sway bars and lowering springs are the cheapest that actually show results. Strut Bars really help out the suspension as well. The suspension needs work to begin with and those parts can be purchased for way less than a supercharger or turbo. You can buy them later after you get your suspension right.

very popular upgrades are trd exhaust and intake. l recomend these because they are directly from toyota and are will not harm your warranty but also are covered under the warranty. im pretty sure its aroubd $500 for the exhaust and $400 for the intake

well, it depends on what u want, power or suspension.

power:
1) aftermarket exhaust (tanabe, hks, greddy, trd)
2) cold air intake
3) pulleys (REALLY cheap, the free up hp as well as increase ur acceleration)
4) short shifter
5) header

suspension:
1) lowering kit (trd, tanabe, hotchkis)
2) struts/shocks (improve ride quality)
3) rear sway bar (front swar bar not necessary unless u plan to autocross, if this is a daily driver the rear sway bar will help u hug corners better.)

power = more things to do

suspension = cheaper (depending on the brand)

if u need help or have questions, send me an email. l might even be able to find u a good price for whatever you're looking for.