This is a more generic reformulation of this question (with the elimination of the Rails specific parts)
I am not sure how to implement pagination on a resource in a RESTful web application.
Assuming that I have a resource called
I think the problem with version 3 is more a "point of view" problem - do you see the page as the resource or the products on the page.
If you see the page as the resource it is a perfectly fine solution, since the query for page 2 will always yield page 2.
But if you see the products on the page as the resource you have the problem that the products on page 2 might change (old products deleted, or whatever), in this case the URI is not always returning the same resource(s).
E.g. A customer stores a link to the product list page X, next time the link is opened the product in question might no longer be on page X.