Bribes in EB are expensive, yes... but sometimes, depriving your enemy of their own armies for your own use is more than worth the cost ("in the right place, at the right time").
Small rebel settlements in the middle of nowhere (relatively speaking) are a favourite target of mine. Even if it's not a particularly good investment economically or strategically, it's at least something to spend money on when you get to the point where you're swimming in the stuff.