There are two main supply resources people use to sell on sites such as eBay, Wholesale and Dropshipping. Each have their pros and cons, and each is very different.
Buying wholesale means you are buying in volume (bulk) It offers you products at a discounted price, the more you buy, the better the price .It's all about buying power, the more a wholesaler can sell of a product, the more he can order. The more he can order, the better price they can secure from the manufacturer. The manufacturer can pass on better prices, because they have the orders to make more product and in so doing, make more money, and the wheels of business turn round and round.
Of course that's the benefit of wholesale, but the downsides are mostly cashflow and storage space!
Using a dropship resource means that there is no volume purchasing, in fact you are buying one product at a time. As opposed to Wholesale, where products are purchased up front, a dropshipping model means that you aren't actually paying for the product until it's sold. So a definite benefit from a cashflow perspective and of course the stock holding perspective as well.
The downside, price. Dropshipping can never deliver you the price that wholesale does.
This is an area where a lot of people can struggle, wondering why a dropshipped product price can't compete with a seller on eBay. Of course the answer is quite simple, the seller on eBay you are comparing a dropshiiping price with is most likely buying his or her products using a wholesale supplier. When measuring the two prices, dropshipping is never going to compete with wholesale discounted prices.
Another two supply resources that should be never overlooked are Liquidation suppliers and second hand. Liquidation suppliers make it possible to buy in bulk, without have the large cashflow that wholesale often requires. Second hand, well we all know that if you can talk a good deal at a charity shop, a weekend market or at a yard sale (garage sale), then a few dollars can go a long way.
My mother had a rather unfortunate saying, "there are more ways to skin a cat than just one" Not quite sure what she ever had against cats lol, but her point bares out in there are many ways of getting into the market, you just have to find the one that best suits you.