'93 Dodge Intrepid wont start please help!

I am a single mother who I think got ripped off. I just bought this car and all ready put over 500 into the engine. Right now I'm having trouble getting my car to start. It won't even click over. It's a brand new battery and I had my alternor checked. I have a little bit of power in my car you can barely see the dome light but the power lock and windows won't work. I do know that I have a small leak by the transmission seal but was told that was not the problem. My car is an automatic. 3.5 liter. With about 125k miles. I don't know if this will help or not but when I was driving the car home I stopped at a red light and all the lights came on as if some one opened the door. I have jump started the car and let it run but when I turn the car off and try to start it right back up I get nothing. Any help would be great! I'm hoping it's a small problem because garage prices around here are killing me!