A GX with mileage that low is a bit of a unicorn, and there probably aren't a lot of examples available to compare the true value to, so the price is subjective and based on what you are willing to pay. That being said, it's still a 12-year old car. At that price you really aren't that far off from a new T4R (50% higher initial cost for something brand new and modern, with a warranty), or a GX460 that is nearly a decade newer (they can be had in the $30-35K range here in the Midwest with <100k on them).
If you are in the market for a unicorn, low-mileage GX that you can drive for another couple decades, it's a rare bird for sure, and the cost might be worth it (to you). I'm guessing that GX's with that low of mileage come on the market very, very infrequently. For me personally, I'd buy a new T4R or a lightly used GX460 over a low-mileage older car at a similar price, as they are a better value, since many parts (plastics/rubber/etc) degrade with time regardless of mileage.
FYI - GX prices in general have exploded, some dealers here in the Midwest are now asking $16-18K for GXs in the 100-150K range that are otherwise clean. Glad I got mine in September of last year before the popularity wave reached the center of the county.