Little Guy Discount Rent-A-Car

I bought a Car from this Dealership and had several problems intermediately come up within their 30 day warranty: Issues with the Battery,the Driver's Side Door and Window, Skipping Transmission, etc. etc.). Needless to say, I complained about a skip in the transmission while the 30 day Warranty was still in effect. I purchased the car with an existing condition (Catalytic Converter needed replacement) this took almost 2 months(30 days after warranty) to correct. The owner had allot of excuses including that the purchased used CAT was "taking too long to get here from Canada." The dealership's mechanics insisted that what I reported to them (skipping transmission) was not a transmission issue, instead they came up with several other excuses on why the transmission appeared to be skipping: Some of the excuses shared by the "Owner" were that the shifting issue was because of the car's age, make and model. All were found to be unfounded excuses. So I purchase the vehicle on 8/23 and after a little over 4 months the transmission finally falls apart. The Owner is accepting no responsibility for the broken transmission because according to him "this occurred after the 30 warranty ended." The issues had been reported prior to 30 days and the engine light that warned of a transmission problem had been shut off by a mechanic months before the transmission finally broke. The car whose book value is under 1,200 will cost me 3,200 by the time I finished Paying it off. Now the Owner wants me to pay 400 dollars for them to replace the Broken Transmission of this Lemon (which is basically what this is amounting to) bringing the cost of the Car to $3,600 dollars - this is for a 13 year old car with High Mileage. Now the owner offered to "put in" the transmission for free as long as I buy the transmission. Being that I am on disability and only get enough money to pay the car note $200 and my rent $700, it means that I cannot drive the car till I get money from who knows where!