Time in quests and shopkeepers

[Jiraaza]

I have an idea about a wandering vendor
who appears at random times, and leaves after a set amount
of time. He only sells one item, which is always magical, but
usually cursed (about 75 percent of the time it is cursed) his
stock will rotate randomly every time he appears, he will
never buy anything, and after someone buys the item from
him he laughs, then disappears. The magical items he sells
if useful are just really weak stuff. But everything he sells
are always extremely expensive (cursed or otherwise) and
completely worthless to resell. I know how to do some of
this stuff, but want to know how to do the rest (randomly
appearing, disappearing after time, or when sales made,
rotating stock...)

[Kirkus]

What I need is a way to keep track of time on the pc so that the pc gives a
message to a messanger and the messanger returns in 17 to 20 days. Can this be done?

I was hoping I could use time as a trigger for a part of a quest. Here is what I want to happen..... The pc gives a message to a mob and the mob is supposed to take that message to another city and return with an answer for the pc. Say the messanger is going from WD to ZK, thats 1650miles or 1210 through the Anauroch desert that is still a sizeable journey even in our modern real world with cars. For the messenger to come back again that brings the total up to, we will be nice and say 2400 miles. On foot traveling 7 to 8 miles an hour and walking 10 hours a day it would take 34 days. On horse traveling 14 or 15 miles an hour for 10 per day it would take roughly 17 days. How can I make this mob dissapear and reapear for the pc 17 days later?

Thanks

[Andreas]

Is it possible to have mobs that man shops based on the month?

[Andreas]

What about a shopkeeper mob that uses a mprog to load items into its inventory for sale? Can it be set to a timer to rotate stock?

[Dalvyn]

But remember that shopkeepers that load items for sale will only sell one copy of them, not more.

[Tyr]

If you want to sell more than one copy, you could put a buy prog on the mob to load up a new one.

Tyr