I had the same "issue" after I reloaded my previous save. Maybe with a new game it's fine. Anyway, it went down to anywhere between 50-1.5k after a week.
3 workshops, 2 caravans and a castle yield me between 300-3.5k (Netto) on a daily basis.
Tho this result is influenced by how many faction I'm war with. Caravans, Castles and Cities make more money during peace time. Probably will need some balancing later on but I'm fairly satisfied with it right now. It seems about right.