There is one near Gongguan MRT station. Come out of the exit next to Starbucks. The shop is on your right before you reach the bus stops where you would catch a bus to NTNU/Shida.
There is one on Hangzhou South Road between the south-east entrance of the CKS Memorial Hall Park and the Hangzhou/Roosevelt junction. It is a consumer cooperative so you have to join.
There is one on the north side of Xinyi Road close to the junction with Yongkang Street. It is number 195 of whatever section that is of Xinyi Road (2?). That shop is one of a chain. There is another branch in Shilin.
There is a little cooperative shop at the entrance to the Ananda Marga meditation centre across the road from the NTNU branch school (Shida fenbu) at No. 99-1, Section 4, Dingzhou Road (near Gongguan).