So what you are looking for would be like the computer sales sites ie dell.com you chose the base model, then are send off to the next page to select/modify the components, add larger hard drive, more ram, programs and so on .. as you select/deselect the components the total in is dynamically changing somewhere on the side.
As is, Zen cart can’t do that.
I’m not a programmer sorry so I can’t tell you how to fix the code, but you might have a few alternatives.
If you don’t have too many of these different options what seems the simplest one is to program this as attributes.
So you have your base horse trailer with price and,
Attribute 1: Exterior
Option 1 – price
Option 2 – price
Option 3 – price
Attribute 2: Interior
Option 1 – Price
And so on
The client selects one of the trailers and then looks at the attributes and options available for modification of such. Attributes give you an option for images, and if you need those larger you might need to consider some of the mods that handle that.
The only thing here is the updated price. So if you really want that to change on the product page as attributes are selected and not only when the customer hits the buy button and is sent to the shopping cart then that code would need to be added.
Alternative 2
more complex and more code rewrite:
Set up multiple categories with multiple products.
Trailers with all the base trailers then one each for of the options.
So you would have Trailer category with products
Trailer 1
Traler 2
…
Then Interior category with products for
Interior for Trailer 1
Interior for Trailer 2
…
And so for all the options.
The option products would each have the different options for THAT Trailer set up in attributes with the price for it, images and so on.
Us a mod that hides the Categories from menus. (check the downloads it’s available and it works nice) Hide all the Option categories from the menu. You don’t want the client going separately to browse. He should only be able to see the base trailers on the menu to pick from.
The idea here is to force the system to send the customer from category/product to category/product in a sequence instead to the shopping cart each time they click buy.
So a customer selects a base trailer, clicks buy and is sent to the Product with the exterior settings for THAT trailer. “Please select exterior”. From there to interior and so on. Each time he clicks buy, the amount for that option is added to the shopping cart, so he has an idea of the running total in the side box.
Once he is done with all the options he lands at the shopping cart.. then he can click on any of the options to go back and make changes if so desired.
As I said a lot more complex to change the code, lots of issues to consider. Like how to deal with the client clicking the shopping cart in the middle of the process? How to stop him or return him to the right place. Maybe disable it unless the condition that all the Option Products are in the shopping cart even if it is the 0$ no change option. “Please complete your selection first” or something like that. And then just the basic, how to force one product to send you to the specific next in the sequence.
Anyway, just some ideas, it was an intriguing question, I read it yesterday and it was running through my mind while I was driving today. Hope it helps with the possibilities of what you might need to do.
Good luck
nev