Now that I am a bit older, broker and dumber, I will suggest that you don't take your suppliers prices as being the cheapest, today I ordered something that my supplier stated was out of stock, their price was $24, I got it from elsewhere for $15.
I have noticed this a lot, if you are selling something, shop around for the best price you can get it for, make sure you add shipping into the equation, no use paying $10 less and being ripped on the shipping.
Do a Google search of the item you are selling, it will bring up lots of different suppliers and prices.
Try to stick to known suppliers, no upstarts that may cause you grief.
I sold something for $15 plus $5 shipping which I got from my supplier for $12 with free shipping, the exact same item was being sold by Chinese suppliers for $2 with free shipping, I chose to go my supplier because of reliability of service, bear in mind that they prolly got it from a Chinese supplier themselves.