I have buying wholesale iPhone cases and tried to sell them on ebay but none sold at all. I am looking for something else to start off with to buy and sell to make some profit.
First lesson, validate your market first. Start with small experiments in selling and marketing before you take on bigger deals. Start with first base before you try for a home run. There is no magic answer - if there were, there would be tons of very rich people which may not make sense. Start doing smart experiments - research, go to conventions, get online, interview people in different markets, look at the trending stats on google and youtube.