Do l really need to get a pricey one ? l heard they all serve the same purpose and buying an expensive one is not very necessary . is this true?

Im not sure on the price but JC Whitney carries that kind of stuff.
jcwhitney.com

Dont cheap out on something that protects your turbo. A new turbo is about 3 grand. Just check for an ST l branded part to be safe.

Yes, they all serve the same purpose, but they are also all priced competitively with each other. Expect to spend about $100 on one. Maybe a little cheaper, maybe a bit more.

The most popular/common brands are Greddy and Apexi.
You can order one off of

slowboyracing.com
nopi.com
machv.com

or many many other sites.

Different turbo timers will have different features. Some can be connected up to an engine oil temperature sensor & so will only let the engine idle for as long as is necessary. Some will wire into the handbrake/park brake sensor (same sensor used to light up on the dash so u know the Park brake is on) so that whilst the turbo timer is operating, if someone tries to steal the car using the engine running on the turbo timer, it will turn the engine off. Some turbo timers can have manual override on the time they will idle, so perhaps longer than the calculated time. Generally the more feature packed turbo timers will cost more, & rightly so. Since its an STi, u should consider one that is compatible with the factory immobiliser so that the turbo timer can;t be used to hot-wire the car & steal it.

First off, u do not really need one. Turbocharged Subarus already circulate coolant through the turbo after the car is shut off. This was more of a definite need on older turbocharged cars. This has been discussed in detail at Nasioc & Subaru themselves have already said it is not necessary. That is why no cooldown procedure is even mentioned in ur owner is manual.

With that being said, if u do decide to buy one, they generally cost between $100-200. Some have additional features such as monitoring A/F ratio, battery voltage, etc., so that is up to u which u desire. The major manufacturers r HKS, Apexi, Blitz, & Greddy. Ensure u get the proper harness for an easier install, & l believe the HKS harness works with the other brands timers (not 100% sure though). It will save u a lot of time & headaches.

http://rallitek.com/avoturbotimer.html Heres a Turbo timer for $150. Rallitek deals alot with subarus and AVO is a good name brand.

you can purchase them online at the following websites that the most popular aftermarket company such as hksusa, greddy, aem and jdm. that l know so far but it may help to look in car mag. sorry - good luck finding it.