You should be able to get past this by updating the server validations on the page. You can update them with either the Validation Toolkit/CSS Form Builder or you can make the update manually. To update the validations you will edit the server validations and select the number validations that are applied to the price and weight, in here specify the European format rather than the US format.
To update it manually you would go into the code on the page and update the following two lines of code:
$WAFV_Errors .= WAValidateNM(((isset($_POST["ProductPrice"]))?$_POST["ProductPrice"]:"") . "",0,1000000,2,",.",true,4);
$WAFV_Errors .= WAValidateNM(((isset($_POST["ProductWeight"]))?$_POST["ProductWeight"]:"") . "",0,1000000,6,",.",true,5);
You will want to reverse the order of the thousands and decimal separators from this (,.) to this (.,) so they look like this:
$WAFV_Errors .= WAValidateNM(((isset($_POST["ProductPrice"]))?$_POST["ProductPrice"]:"") . "",0,1000000,2,".,",true,4);
$WAFV_Errors .= WAValidateNM(((isset($_POST["ProductWeight"]))?$_POST["ProductWeight"]:"") . "",0,1000000,6,".,",true,5);