jQuery("#merch .proprice").val(function(index,value){
    price = jQuery(this).parents(".row").children(".col1").html();
	price=parseFloat(price.substring(1));
	price+=3.00
	return price;
});

Get the FireQuery (http://firequery.binaryage.com/) extension for firefox and then use this snippet to auto set prices for the merchandise tab.

jQuery + SmugMug Merchandise Price Set

jquery

ActionScript 3