Everything is absolutely stock: 115 HP/122 lb-ft torque/2.0L Inline4. ()

Problem= The tranny is done for

I can't afford to spend $5000 on a transmission, but I do need a solution.

What is the best transmission to buy for under $3000 ($2999.99 doesn't count). It's a 4-speed automatic overdrive (also stock), and I don't have enough car knowledge to turn it into a manual (I'm only 15).

Also, is there a low cost high quality chip for increased HP I can buy for this car?

Please help me out here.