Those aren't necessarily going to offset nice and equal like that. It isn't even likely that the number of sales lost, due to value people are holding out for, will match up the value BTC actually lands at.
You have a couple things in your argument here:
1. You're working from the assumption that bitcoinstore is losing sales from customers not wanting to spend money due to "deflation". Unless I missed it, you haven't provided any evidence of this outside of just saying that's the case. It might seem right in your gut, but you are making the claim and thus need to provide some shred of evidence. And no, you can't base your argument on pure speculation alone because that's not an argument.
2. You are assuming people aren't smart enough to convert USD to BTC. If I need to buy a computer and can save 10% value by buying from bitcoinstore with BTC over USD at amazon, I'll just buy some BTC with USD and then make the purchase. I haven't bought a computer, but I have done this exact thing for other items from a variety of bitcoin stores.