The reason there's so much of it is because NO ONE is buying it!
They probably love it in japan.
I don't have/use any special filters. Long exposures? It's large format, short exposures don't exist outdoors in the conditions appropriate for shooting velvia. haha, tell fuji that. For me, wind is the killer. It's always a waiting game and very often I don't get the shot I want because I don't have iso 100 film on hand.