I don't know of anyone who has tuned a base ECU on these cars. The 05-06 Vibe GT can get a tune from R9K Tuning (I believe that's the correct order of letters).
Depending on your plans (as in boooooossssttt), standalone engine management is usually the way to go. A tune on these with things like exhaust, intake, etc. really doesn't accomplish much of anything.
You will get very little in return for your money if you do not super charge or turbo it. To do either of those, you will spend a lot of money to do it right.