Not exactly what you are looking for but for GS-
SeiyaJapan and
Higuchi are two trusted Japan-based online shops who may be able to source for you. Seiya is Tokyo-based and Higuchi has a storefront in Oita (Kyushu). I also bought two mid-range Seikos (a Sumo and a SARB) from this Rakuten shop with a good reputation:
https://www.rakuten.ne.jp/gold/10keiya/ Stateside, you can also try
https://timelessluxwatches.com/ in Dallas or FineTime in AZ:
https://www.azfinetime.com/