Hi Mark,
Simply Wholesale is not in our directory but should be safe to deal with. Their site was last modified last year but they have been in business since 2011. They accept safe payment methods such as PayPal, or debit/credit cards. Also, they offer a 14-day money back guarantee if you are not satisfied with their products.
If you decide on re-selling their items on eBay, it's best to compare their product pricing with eBay first. Also, keep in mind that wholesalers also sell on eBay. The sellers who make money on eBay spend a lot of time doing market research, experimenting with different products, and looking out for special deals from suppliers.
So if you want to continue with this supplier on eBay, vital research is the key. Purchase your items in bulk to get a much lesser rate! Others keep away from eBay competition and sell on other auction sites such as Addoway, Bonanza, Overstock, eBid, BlueJay, Amazon auctions, Online auction, eCrater and Craigslist.
Hope this information helps.