Holden hit the nail on the head- the biggest headache for any retail business is managing inventory. You need to consider issues such as: 1) Where will you keep the products, 2) Taking out insurance in case the inventory gets damaged or stolen, 3) Having some sort of return/recourse plan in case your supplier sells you a lemon, 4) Inbound & outbound shipping costs, etc.
Also, I would sit down and really think about exactly how much money you're actually going to make when selling items. As Holden said, and as I've seen when buying CE items on eBay, there's a ton of similar stuff being sold out there. In fact, for most items you can detect that a market clearing price has been established that really doesn't provide much profit to the seller. When you take into account things like sellers fees, shipping, storage costs (if any), insurance costs (both storage and shipping related), and potential losses (from non-paying buyers, defective items, etc)... how much are you really going to be making? How much volume do you need to move to make a "substantial" amount of money that justifies being in business?
Most of the best eBay businesses that I've dealt with, at least for CE, have had some form of B&M store sitting behind it (e.g. Local CE shop in California) to help manage some of these issues.
Not saying it isn't possible to do, just make sure you consider ALL of the costs.