Trying to buy a car in philadelphia need help cause i don't have good credit. Thanks?

Does anyone know a good dealership in philadelphia where i can get a car where i don'tt have to put down a hugh down payment and my monthly payments wont be outrages? Please help me my mom is willing to cosign for me though she is only about $1200 in debt butdon'tt know her credit score. If anyone has any helpful information i would appreciate it thanks.