I had just conquered the Teutonic order and I was struggling financially afterwards. I had -0.1 ducats per month, and only about 3 gold. So, I struck a peace deal and decided to fully annex the Teutonic Order and sell it according to culture. Memel is Lithuanian, Neumark is Saxon, (And a part of the HRE so I didn't want to get lubed up.) And with the exception of Kulm, (Which has Polish culture.) Danzig, and the one province that connects Danzig to my mainland I sold the rest to Pomerania. Why I say it shouldn't affect non-cores is because there are several times in history when territories have been sold where nothing happened. As an American I can name several times when we purchased territory and no one cared. Gadsden from Mexico, Louisiana from France, Alaska from Russia, And Florida from Spain. There's also several times we just gave up land to other countries, especially in the Pacific and most notably the Panama canal. As I said before, literally no one cared. Most people if you asked them wouldn't even know this happened. Now, if it was a CORE I would understand. Selling provinces shouldn't just take away your prestige, there should be other factors that are taken into account.