Where can I buy a ps3?

I want a ps3 but it would take 6 months to save up $500. I'm looking for a job but I live in a small town of Plum Branch SC. And with gas I can't afford to go to another city to find a job. I can get some money from my mom and pay her back but I can't get $500 from her. Is there any websites I could buy one around $200 to $300. I hope someone can help me.I get $20 a week so you know