Casio G-Shock Gravitymaster GR-B100 (GR-B100, GR-B100-1A1, GR-B100-1A2JF) , Current Prices, JDM Listings, Market Analysis
The Casio G-Shock Gravitymaster GR-B100 sits at the professional end of the G-Shock lineup, built around aviation-oriented features and the Gravitymaster name that carries real meaning among pilots and outdoor users. Tonbo tracks the GR-B100 because it surfaces regularly in the Japanese domestic market, where pricing often diverges meaningfully from US retail and resale levels. The current US median for the GR-B100 puts it in accessible territory at around $200, making it a practical target for buyers willing to source from Japan. Reference numbers in circulation include the GR-B100, GR-B100-1A1, and the JDM-specific GR-B100-1A2JF.
Current US Market Value
The GR-B100 price in the US currently sits at a median of $200, with the middle 50% of transactions falling between $150 and $260. That $110 spread tells you the market is not particularly tight, which is worth noting before you anchor to any single number. One important caveat here is that this analysis is built on a sample size of five comparable transactions, flagged with a 🟡 Limited comps rating. That means the median is directionally useful but should not be treated as a settled figure. As more sales data accumulates, that range will sharpen. For now, $200 is the working reference point, and anything closer to $150 warrants a close look at condition and completeness.
Active JDM Listings
There are no active Japanese market listings for the GR-B100 in the past 14 days. That kind of dry spell is not unusual for a model that moves in irregular cycles through Japanese platforms, but it does mean there is nothing actionable to evaluate right now. When inventory does appear, it tends to show up across the major Japanese auction and marketplace platforms that Tonbo monitors continuously. Check Tonbo's live deals feed for the moment new GR-B100 listings clear the surface.
- No listings detected in the past 14-day monitoring window
- JDM variant GR-B100-1A2JF appears periodically but not consistently
- Japanese platform inventory for this model tends to cluster rather than flow steadily
- Box and papers availability varies significantly when units do appear
- Condition grading across Japanese listings for G-Shock models ranges widely, so photos and seller ratings matter
Recent Alert History
No strict alerts or opportunity alerts have fired for the Casio G-Shock Gravitymaster GR-B100 in the past 90 days. That reflects a combination of thin Japanese inventory and the limited comp pool on the US side, which makes it harder for the signal engine to confirm a genuine gap worth flagging. It does not mean the model is a poor target. It means the conditions for a high-confidence alert have not aligned recently. When a credible listing does emerge at the right price, Tonbo's signals page is where that fires first.
Japan vs. US Price Gap
The potential case for buying a GR-B100 for sale in Japan rests on a price gap that can open up when Japanese sellers price to local demand rather than global resale comps. G-Shock models in Japan often trade close to or below original retail when sellers are moving used inventory quickly, and the GR-B100-1A2JF as a JDM-configured variant does not always have a direct US comp to anchor against. The primary risk here is the one that applies to most JDM sourcing at this price tier, specifically condition variance and the challenge of verifying wear, function, and original accessories from a distance. With a comp pool of only five transactions, there is also meaningful uncertainty in what "fair value" actually looks like, which cuts both ways on any given deal.
Track Casio G-Shock Gravitymaster GR-B100 on Tonbo
Tonbo is free to start at tonbomarket.com/dashboard under the Collector tier, which gives you a five-model watchlist and no card required. Add the GR-B100 to your list and Tonbo will monitor Japanese platforms continuously, surfacing new listings and pricing shifts as they happen. If you want real-time Discord alerts the moment an opportunity clears the threshold, the Member tier adds that for $10 per month. Given the irregular inventory pattern on this model, an alert setup is more practical than checking manually. When the next GR-B100 appears at a price worth acting on, you will know immediately rather than finding out after the fact.