If you are located in the United States, these will be your best options. Each vendor has their own price point indiciated by ($). Please let me know if you know more suggestions.
Amazon.com ($+/-)
Common website to find go equipment. Search terms like “go board” or “go stones”. You will get a variety of listings.
Click here for Cheapest Bundle | 19×19 ($28.99)
Baduk.club ($)
Go player community that sells reasonable recreational equipment for club members. It also has japan imports.
Click here for Club & Tournament Gear ($)
Click here for Japanese Vintage Gear ($$$)
Kuroki-Goshiten ($$$)
The highest quality stones and boards money can buy. It might be cheaper to get it on your trip to japan lol.
Click here for the Manager’s Recommendation #1
Song Yun Wéiqí ($)
Best for value and lowest price point. Chinese online retailer for yunzi stones. Recommend the go set bundles!
Click here for the Cheapest Bundle 9×9 | 13×13
Yellow Mountain Imports ($$)
Online retailer for many traditional board games. Good choice for affordable prices. It has 9×9 and 13×13 boards.
Click here for Beginner Set 9×9 | 13×13 (best value)
Temple Go Club 