Transmission pressure switch??

My car (2011 Holden Cruze 90k odo) has been having trouble switching between gears which is weird cause it's auto but anyways. But lately I've been driving like 80km/hr and it'll like rev up to 5, jolt a bit, then go back down to 2ish. Idk how else to describe that. Took it to the mechanic, came back saying "transmission: transmission fluid pressure switch 3 circuit high voltage (symptom 00) - test failed since history DTC, current DTC since power up." Yay. They said it's a small $150 thing to replace, but because of its location, the price will go up a bit, but still around like $300ish. Took it to a transmission specialist, for him to tell me a very rough quote is like 8k to get it fixed. I bought the car for 7k 2 years ago :/ so now what? Do I fix it? Do I sell it? Is there another option? Has anyone had this happen? Any advice will be appreciated!