If you reported the e-bay sales on your income taxes as income, you have the proof you need. Also your assets (such as bank accounts, savings, car, property, count for 1/5 of the shortage - if you are short $1000 of the requirement, then you need $5000 in assets). Hopefully this will give you some ideas. I researched this since I was self-employed when I initially filed the I-129F. Of course, by the time the INS finally gave us our interview, I didn't need the co-sponsor, assets records, etc., because I had gone back to work.