DHP tuners will run around 300 bucks. ( not made anymore, must find them used)
HP Tuners will run 500. You will get 8 credits aswell when you buy it.
Tuning is not easy and takes a long time to learn and no one is a master at it.
HPT has a huge forum loaded to the brim with how to's and stuff to read and to get a basic picture of what is involved.
If you are willing to buy them, you must give alot of time to learn.