Something about a green $200NT dollar bill just looks fake to me!
A lot of people avoid that bill because it is the only one with a picture of the dictator Chiang Kai-shek on it.
There are a couple of old coin and stamp shops near the main post office. Hard to locate, they are on a little motorcycle lane just west of the post office's Po-ai Road entrance. If you stood at that entrance and looked right you'd see the old city gate. If you made a triangle with the last point to your left, that's about where they are.
I have two "yi jao," one is year 44 (1955) and one is year 65 (1976). They have different designs.
I also found in pocket change two commemorative NT$10 coins. One for the 90th year of the ROC with the good doctor on it and the other for "Guangfu" (retrocession) in 1995. Did someone spend the special commemorative sets?
I used to work in a pizza joint where old people would sometimes come in and spend silver certificates, indian-head pennies and the like. Some appeared not to know what they had and others had a sly, "Better keep that out of the till, son" smirk.