If you really want the main product image centered, all you need to do is add to your stylesheet_main.css

#productMainImage {float: none;}

This will put the description below the image without any clear: both; required.

Then if you want the price on the right, find this in stylesheet_main and add float: right; as shown

#productPrices {color:#C70E06; font-family:tahoma; font-size:13px; line-height:normal; font-weight:bold; float: right;}