its not that simple bro.
you have to do your research, find something you know something about, see what price people are selling it at on ebay and see if you can find it cheaper. if you can't find a supplier that gives you the profit margin your looking for then maybe you should try another product.
sometimes it can take hours or even days or longer to find the right product that you can sell for a profit, the key is to bring value to the market and people will buy, if the product is cheaper or better somewhere else you will never get sales.
my suggestion to you is try china. you wait a wile to get your items but they are hard to beat on price just make sure you get generic items (no brand names).
also maybe high profit margins are not so easy, you could try low profit high volume sales. takes longer to get there but its more consistent in the long run.
I'm really sorry if I'm telling you stuff you already know, I don't normally give advice.