Slitherine

Most of the time, AI factions are offering money and stuff in exchange for 2 of my provincial units.

Does giving these 2 units cost me anything? I didn't notice cost of the units increasing. It doesn't seem to reduce my money or equipment. Is there any cost to me?

They cost you 75 money each, no metal or manpower. So make sure they are offering you enough money and other value to make it worhwhile.

More of a problem is they never seem to offer their provincial units to you.

Lagides offers aegyptian skirmishers to Rome in my game, but it's the first time

Dalmatia offered me a provincial unit.