Hi Hujimy, welcome to SaleHoo.
What to sell?, that is one of the most asked questions we see on the forum, so you may expect it to be the easy to answer ...... but unfortunately it's not!
There are a whole lot of factors in play when working out what to sell. The best place to start is knowing what type of supply method will best suit you. Drop Shipping, Wholesale, Second Hand and so on.
Each supply method presents different prices, so the opportunity to make make money on products sourced through them can vary wildly. It also depends on what avenues you will be selling through, as some marketplaces are far more competitive than others, and that of course effects selling prices.
Research is the name of the game, and my guess is you are going to have to do quite a bit to provide yourself with some accurate answers.