We offer very good price -- 93% of gold world market value.
Current gold price - ~ 1600 USD (actually, it's a little higher than this, but to make things easy...)
1 oz ~ 28.3g
56.5 * .93 ~ 52.54
Current market value of Bitcoin = 13.5 at time of this post (Mt. Gox price)
52.54/13.5 ~3.88 BTC per gram of gold
Currently the calculator on your site offers 3.57 BTC.
Why the difference between 3.88 BTC and 3.57 BTC? This doesn't look like 93% to me.
However, I think your business plan is brilliant. At this time, I would absolutely love to have a gold-to-bitcoin business.