Format Buy Button using shortcode in post

How can I:

1) format the meta of the shortcode to ONLY show the buy now button, not the price?
2) center the button in the page?

Any css hints to do the second, and code or shortcut changes to do the first?

3) also, I have a floating div on the page that is displaying the post, kind of a footer, like WPMU has here for their header bar. I may want to put the buy button there as well.