A suggestion that was inspired by one of the dialogs, maybe occasionally, you get an order in advance of the sale. Like a bit of paper that says they need 3 daggers in 4 days, something like that.
Also it'd nice if polite(the ones that don't say things like "SWORD NOW! Etc.") customers said Thanks or something as they left or picked up the weapon(so as not to slow down gameplay).
A couple ideas for adding difficulty, hunger(once a day, with a slowness debuff if you go so long without food), rent(untill you either buy your house, or a new one.) perhaps you risk getting robbed, unless you hire a guard(just because you make swords, doesn't mean you know how to use them). These could be tied a difficulty setting, or have individual settings.
Well that's me throwing my hat into the ring, I hope these help.