You might have overlooked something when pricing your Brimstone, Blizzard takes 15% right off the top for sales. So $90.30 * .85 comes out to $76.75. And the price of Bitcoin is greater than $7.675/BTC right now. And that's only if you're cashing out to Blizzard bucks, if you wanted to cash out to Paypal there's another 15% fee bringing you down to $65.24.
Neither of these fees affect somebody who wishes to craft with the items. Its not the sellers responsibility to cover the fees if the buyer wishes to cash out.
Bitcoin is the solution to bypass paypal and other corporate fees. I don't see why they would be factored into the price.