There’s a Taipei bias on these forums so let’s correct it.
The next time I’m in Kaohsiung or Chiayi, where can I find a decent second-hand book or music store? Let’s build a database here.
In Tainan, there are two second-hand bookstores with a large selection of English-language books:
Chung Yi Road, Section 2, #6 (corner of the You-ai intersection). English books on second floor.
Beimen Road - down from the Chingnian intersection (railroad crossing). There are two bookstores on that block; the second one has English books, conveniently located in front of store on the sidewalk.
Also on Beimen, a couple of blocks down from the train station, is a second-hand CD store (opposite side of street from Caves bookstore).
Another second-hand CD shop is round the corner near the Shengli/Dongning intersection. But the best place to pick up CDs is Dirty Roger’s pub, right next to the Dongmen bridge - drop in and ask him sometime for a burn.