Hi Ryan,
Singapore DOES have an Astro shop - Astro Scientific Centre Pte Ltd is located in the Singapore Science Centre in Jurong, about 10 minutes walk from East Jurong MRT station. It's about a 20 minute ride from the city by MRT.
It's easy to find using Google Maps or similar.
Www.astro.com.sg
I spent a very pleasant hour there a couple of weeks ago talking to Albert and Jeffrey Lim.
Albert is the author of a number of astronomy books and is very knowledgeable.
I bought some accessories while I was there and was happy with both the price and service.
They had mostly Celestron and Orion scopes on display, and a very good range of accessories.
If you make a purchase, take your passport. They will process the purchase so you can claim the 7% GST back at the airport.
I consider them well worth a visit.
Cheers Phil