" buy this item if its cheaper than XBTC? "
This is the most important part, cheaper then with dollars and automatically that means cheaper then on most other places. I like to buy quality stuff, and cause I dont have big salary I need to save and wait for shopping nights, sales to buy something cheaper.
You have a great idea here, this can popularize bitcoin as currency. People will convert fiat into bitcoins if they can save money in that process.
You need to draw up a realistic business plan, remember that profit is what youre left with after paying for everything.
