The fee percentage will be critical if you have a low profit margin because it is calculated on the TOTAL sale including your costs such as postage. So, let's say for example your $100 sale includes a 50% profit margin of $50 but your postage costs were $15.00, then once you subtract the eBay and Paypal fee from the $35.00 gross profit, you are left with about $20.00 over all take from the sale. This doesn't take into account your labour and running costs, such as petrol to lodge the parcel, electricity, printing receipts, phone calls or other communications after the sale, subsidized postage by overseas governments allowing their people to list items cheaper on eBay etc... Think very carefully about selling on eBay as a business venture as it could cost you more than what it is worth in the long term.