Limey,
You might find them in iRun, a triathlon shop at 1F, No 131 Sec 3 Minquan E Rd. I’m not promising they stock Speedos but they do have goggles and stuff. Ring them first - 2517 6030.
There’s a sports shop about halfway up Shita Rd that has a good selection of speedo goggles (about 5 or six different models). They stock the more conventional, training style goggles aswell as a couple of racing style models.
There is a swimming shop at the end of my street. I’ll paddle out to it and see if they have some. They sell speedo trunks so they might sell the goggles.