Cell phone help needed

I will be visiting Taichung on business next week and bringing my unlocked cell phone which will work in Taiwan. The only think I’m missing is a local sim card. I already have the phone, how easy is it to get a sim card for pre paid service and where can I get one? How much do they cost? Thanks.

They’re about 600NT (around 20US) and I think you need a passprt to get one. They are no longer availible at 7/11 (etc.) but finding a cellphone shop that sells them is easy enough. You can get refill minutes from 7/11 (etc.)

So sim cards are about 600NT, is that the same with all carriers?

I just arrived and was planning to bring my cell phone, but it broke before I came. So I have to buy a phone and a plan - where is a good place to do that? I realize there will be a lot of them in Taipei, but someplace reliable from which I can buy a phone and SIM card around the Gongguan MRT stop would be best…I haven’t got a clue how to go about doing this!