Hiya - not sure what price is fair, so please let me know what you think :)
Clarification of the requirements:
Basically, we just need a way to display many products on one page, and to allow users to order those products without having to refresh the page every time.
I imagine the easiest way to accomplish this would be to allow the administrator to turn on a feature called 'Express order page' in the 'Marketing )) Cart Plugins' page in the admin area, give the link a display name, and set how many products to display on each page. This would create a link in the category box (displayed on the left in the demo) that displayed ALL products in the database, with pagination as mentioned above e.g. 50 products per page.
The products should be grouped by primary category, and the categories should be ordered in the same order as they are displayed on the LH menu.
The express order page needs to allow items to be added to the cart without reloading the page, just as is done now at www dot cufflinks dot co dot nz - this is an inbuilt option in Pinna cle Cart.
Actually, a very simple way to think of this is like creating a category called 'ALL', which is then displayed as per demo dot pinna cle cart dot com / catalog / Notebooks_Laptops-1-1 dot html
Does this clarify things?