I was wondering if there is an easy way to offer a one time charge on products. i.e. setup charge of $x if you want the item personalized. I was trying to do a drop down form that would give the option.
If you have Manager or Pro you can add to the product price via the Ordering Options selections. See the 'Special Rules' section of the Ordering Option documentation:
One option would be to use subproducts (Manager or Pro). That way so long as the subproduct (customization) quantity did not change then it would be a one-time charge.
Question: is customization an offer with all of your products?
The other option (if you have ShopSite Pro) would be to add a surcharge pull-down menu in the shopping cart. This feature is found under Commerce Setup > Order System > Shopping Cart.