Peachmonkey : Practically, some TT comes with extra functions, but again the main function is just as a timer. Talking about the price, its just that turbo timers are getting a very common gadget in a car so there wise price is depreciating. A turbo timer can cost from RM70-RM400.
Some turbo timers just with normal functions can cost RM200++ such as Apexi or HKS because you pay for the brand.
Have seen some turbo timers that can capture top speed, 0-100Kph etc etc. Also turbo timers are now all fully automatic which means, you can set a preset amount of time for the engine to shutdown after the key has been turned off, or run it on auto mode whereby it will calculate how long the engine has been running and from there automaticly set a flactuating time to shutdown the engine after the key has been taken out.
Hope been a help...