Relation from registration to order line-item or product

I am trying to create a view that lists each registration and is grouped by a field on the product it was created from. If I could get to the line item directly, that would work, but because I have to go through the order, I have problems differentiating when there are multiple registrations for different products within the same order.

The goal would be to list a registration and the price paid for that registration. Going through order works fine when there is only one registration in the cart, but I can't guarantee that in all cases with my workflow.