It depends on what specifically you want to sell and how fast you need them. You can always find anything on Alibaba. There are usually minimum order quantites though. Those are actual manufacturers, not drop shippers so you would need to order the product(say 10 dvd players for example) and have them shipped to you, and then when someone buys one from you on eBay, you ship it to them. You will get the best prices from manufacturers 1st, then suppliers/wholesalers 2nd, and then drop shippers 3rd. Drop shippers might not have a minimum because they are drop shipping so they know you are filling 1 piece orders most of the time.
Wholesalers will have minimums also, but usually much less than a supplier. If you decide to check out Alibaba, ONLY DEAL WITH "GOLD SUPPLIERS!" There are a lot of scammers on there too, so only gold suppliers so you know they're legitimate. You can always negotiate price and minimum orders with manufacturers on Alibaba as well. Keep in mind, most of the time the products are made in China so if you get delivery coming by cargo ship, it will be about a month before your order gets to you. You can also ship by air, but it's more expensive.
Also, if you need anything in China: a specific product, or brand, or suppliers, you can check out ETO.cn. They have a ton of very valuable services to get you whatever you need from China manufacturers. Good luck.
P.S.- Electronics don't have great margins, and eBay selling prices are typically less than Amazon's. You can sell at a higher price on Amazon, and Amazon buyers don't care they will buy it. They usually aren't price conscious buyers. They know what they want, they are ready to buy, and they buy it from Amazon because it's much more trusted in most people's eyes than eBay. Even though both are mainly made up of 3rd party sellers.