Envoys staying at the post house don't have to pay, and some envoys from tributary states even stay in the post house for three to five years and that's quite common.
You can live without spending money, but you must pay for food, drink, and clothing.
Especially food; the post house doesn't provide three meals a day, so you either pay to eat and drink at the post house, or eat outside.
Most people in Chang'an surprisingly eat white flour and white rice, which in their country, even the nobles can't afford to eat for three meals a day.
They didn't bring much money, mainly because the currency is different, and silver is valuable in their country, and they didn't bring much of it.
In the end, they had to sell some of their precious items to exchange for money, and a lot has been spent on social interactions recently.
