Well it's not wholesale, but I've made Power Seller on two separate eBay accounts in the past with nothing but, Second Hand. Nothing specific, just general, although items that I knew there would be a market for.
I would work on a bare minimum of 100% margin, but getting 300% mark-ups was quite normal. The other huge advantage was the constantly changing stock profile which kept a constant flow of regulars, as well as the low outlay for stock.
If I spent 100 on a weekend, that would make me 2-400 during that week. If I spend 300 on a weekend, that would make me around 6-1,200 for the week, and I would struggle to keep stock numbers up.
Most people spend so much time looking for suppliers of products that they are going to make 5-10% on max, and they ignore items that they walk past everyday that could be generating plenty of cash!