Let me see if I understand this correctly ...
For $200, I get an Add To Cart button that does just one product per click.
If I want to add 2 products with just one click, I need to pay $400.
Um, yeah, that dog ain't gonna hunt. That's not an acceptable answer. Nowhere in the documentation for eCart does it say anything about this restriction. Or that you need another $200 product to do something that's pretty darn basic in business.