To the last question first, you have to contact the suppliers directly yourself. No requirement to let them know where you found them, but they would probably appreciate it anyway.
In regards the price, it's not at all unusual to find this, most do. The thing you have to remember is that when comparing prices from a supplier against a seller on eBay, you have to make sure you are comparing apples with apples. For example, is the supplier's price a dropship price or a wholesale price. If wholesale, what size volume is that based on and can you do better with a higher volume purchase. With the seller, are they buying in wholesale, if so what volume and what margin are they selling at?
Is the seller actually a wholesaler themselves and they are using eBay to sell their own products direct to the public?
You see it's never quite as simple as just matching prices to work out what's happening within a market like eBay.