I have never seen a factory suspended-style seat before on a ladder stand. (not saying they may or not be out there) I have only seen them in climbers. but there are some nice seat cousions out and I guess you could always cut the steel mesh out and sew up your own suspended seat. biggest consern with that would be leaving that type of seat out in the weather, wouldnt think it would hold up long and most ladder stands are big and made more to leave in untill after seasson or I know a guy that leave his in year round. he packs his own seat cousion in with him.
I made some back rest and seat cousions for my two from an old couch seat cousion. but I still only leave them in for maybe a week at a time. weather is realy hard on that stuff.