Performing an upgrade is very much like starting from "scratch" on a new website, with the exception of the aesthetic design / logo / header, etc. The program has to be reinstalled, the database updated or replaced, the old design files updated to the current version and more.
To save you money, I start out with a "base" price and then charge for any Zen Cart modules you might have installed. If you need a quote because you don't know exactly what mods are installed, fill out our Request For Quote form (opens in a new window) and I can give you a firm quote with discounts for the mods you need installed.
Please keep in mind that when new versions come out, not all mods will work with it until the mod, itself, has been upgraded. You may lose mods you currently have that you use, and you may choose to have me UNinstall mods that you no longer use.