Whats the best kind of hair extension for me? Please help!?

Okay well two weeks a had a haircut gone wrong/: i told the lady to get me short layers but keep my length (it was about shoulder length) She messed up my hair it looks like a mullet if i straight it the front is as long to my lips and the back is the same except the back i have a SMALL layer to my neck i hate it i cried so much when i saw it i cant stand it any more i hate i cant do a ponytail am sure on getting extensions i just don't want clip ins because its to much to put them on every day and i still cant do a ponytail easily so is glue in better or sew ins? where can i get them online for under 100$$ even if my hair is short is Pretty thick so i need a good amount am going to get them applied at a beauty school they charge 90$ to put them on so whats better and where can i purchase them?