In my recently completed UP campaign Venice declared war on me after I conquered Naples, So i sieged it. I beat their sally back, but a unit escaped with enough men to keep a garrison. Then my ally Genoa comes in and jacks the province from me! I then bought it for, no lie, 1 million. they wouldn't go lower. Every other province I bought ( New York, Goa, New Andulisia or whatever Colombia is called) for 300k or less. Of course 1 million was only about 1/10 of my treasury at this point so it didn't really matter.