I am not 100 percent sure about this, because I am in the process of starting something myself. If you are buying stuff and paying tax, you shouldn't be.. if you have a business. You buy tax exempt, and if you "use" it, you pay a use tax on it. If you sell it, you pay a "sales" tax on it. If you use it and sell it, you pay both.
Also on the ebay deal, I sell stuff on ebay as well, after you sell something small, and pay ebay listing and then if it sells pay the selling fees, and then if someone pays with paypal, pay the paypal fees, there is not much profit left, if any. But it is GREAT advertising. Most people that I have sold flies to in the past, have emailed me later, and wanted more when those ran out. Then I just sell them straight out, and do not have to pay those ebay fees.