Your effort in alphabetising is more than most jumbled people do with their stuff! I think people love browsing stuff and see what catches their eye and if not, they can search for a player.
Agree a long thread seems okay but I think the issue is if the seller then adds cards or changes prices, as a buyer I find myself debating whether I can be bothered looking again. Maybe it's by player or team/alphabetical, but maybe Autos should be all at the top? On OZCT I think most look for Autos, Rookies and Old School, whereas inserts and Mem seem more popular on Facebook groups. Just my impression on here over the last couple of years.
Maybe Admin could consider creating a separate Sell/Trade category for Mid/High End Cards, say $50AUD or more cards? Might help give those cards focus, but also separate threads to make it easier for those looking around.
You spend a lot of time making it easy for us to find stuff as in individual players, might be harder for set chasers, nothing wrong with how you do it.