I usually search by card to find a card or two that I want the most.
after I add those to my cart, then I filter to just that seller to see their other inventory, and add cards from there until I get to the desired number of cards that make sense for the postage cost and total budget.
most of the new look seems to me to be on the 'surface' and once you search something or navigate somewhere else it goes to the old familiar menu (at least that is my perception as a regular user but not a seller)
mark