My gears seem to be stuck in low and i am uanble to drive without it reving up. I was told by a mechanic it could be the tipm and if so it would cost $500 but it would need to be diagnosed first at $150-200. Does this sound right?? Or could it be something simpler??

 

Could be lots of things. Your transmission has gone in to "limp mode" in which it stays in 2nd gear so you can drive it to a repair facility with the proper diagnostic equipment to read error codes which will be stored in the computer. Not any code reader is capable of extracting all the error codes which may be stored in the computer. Sophisticated equipment sufficient to read all error codes is expensive and requires training to use properly. That's why they charge you a diagnostic fee, but some places will roll the diagnostic fee into the repair cost if you elect to get it repaired at their facility.
Take it to a reputable transmission shop and have them hook it up to their equipment to find out what is going on inside. It could be something easy and cheap to fix or it could be something serious and expensive, but until the codes are read properly, we are just guessing.