Based on my own experience, the money you can earn depends less on the products or the suppliers, but well on the websites you are used to advertise on.
Ebay is a very bad place imho : since the competition is hyper-present and since many wholesalers are ALSO selling on ebay, I can't compete, unless I find new attractive products. Then, for a couple of weeks....I make some money. Otherwise, I cover my expenses ( Ebay, Paypal), but I don't get any significant profit.