You got to find a product where the margins are good. This is your biggest problem if you're going to drop ship. Your margins have to be excellent because eBay takes ~10% in fees, PayPal ~3%, Fraud depends on the industry but let's say ~7% to keep this simple, and most people seem to demand free shipping ~10%. You got to remember eBay fees are taken from revenue not profit; so that 30% of revenue will probably be more like 50% of your profit... and don't forget the tax man if you're going to build a serious business.
Effectively if you want to make any kind of real money, you have to find items that you can sell for double the price you paid. This is extremely hard in the drop ship business as there are people out there willing to make a few pennies on a sale and pretty much every item that can be drop shipped, is already being drop shipped.
Personally, I'd avoid eBay for drop shipping just because it seems easy but long run you're better off with your own eCommerce site. I would build a site on Shopify, BigCommerce, or something like that. Market it as a proper business and grow into a well established expert on the niche you're dealing in. You'll make far more money as your only fees when someone makes a purchase is ~2.5% from your card processor and the fraud rates are much lower. eBay is easy to fraud so most people go there. Suddenly your margins don't need to be nearly as high to make a buck.
