The local name varies: 蓮子豆 lian2zi3 dou4 (lotus seed beans); 雪蓮豆 xue3lian2dou4 (snow lotus beans); 雞豆 ji1dou4 (chick beans/peas). Be careful not to accidentally buy lotus seeds, which look very similar and have a similar name (in the first case).
100+ per can is obscene. $35-ish is reasonable; that’s what they sell for at the restaurant supplier I discovered this week, and they have dried, too (sorry, OP, I know it’s not in Taichung, but you could call them and see if they’ll ship COD or after an ATM transfer – if so, let us know, as that would be a major resource for those Forumosans not in Taibei):
P&P Food & Spices 東遠
Taibei, Zhong1zheng4 District, Jin1men2 Jie1, 9-14, 1F
This street runs southwest off of Roosevelt, just southwest of Shi-Da. Take Heping westward to Roosevelt; turn left, go about 200+ yards, and turn right; after a ways it’s on your left (small entrance, not well marked)