virtuemart update from cvs

currently we sell products from pixmania-pro in our Joomla virtuemart web shop (means dropshipping the items) We are facing some problems with orders who are not in stock on pixmania-pro website so we need to have cronjob which will update our products with the live feed of pixmania problem is that pixmania is excluding vat, means we have to either add the tax or set prices without tax, and add them later. Also must add a fixed percentage for our profit, if possible also percentage, but based on price. Like if a product is 1000 euro, it would be way to much to charge 5 % profit on that, so we need to consider a ratio for that the excel is coming live from [login to view URL]