You are a victim of YC's marketing. First of all, if you don't need their money, don't sell part of your company to them. And, if you do need their money, don't make it so obvious or you'll have no room to negotiate the equity you are selling them: people keep saying $15,000 for 6% but those are just averages--the equity range I have heard about was 1.5%-12%. I think you would be a 12%-er for sure.

If I had a good idea that I believed in, I would go to my friends and family and ask them to loan me $2,000 a month for eight months. If I succeeded, I would pay them back their money + interest + whatever I felt like giving them as a gift. If I failed, I would get a real job and pay them back in a few months time.