The 1991 dated book Hawaiian Money Standard Catalog 2nd Edition by Medcalf & Russell assigns a catalog value of $20. There is no population or rarity assigned.
The 2008 dated book So-Called Dollar by Hibler and Kappen assigns a catalog value in the range of $75 to $300 in uncirculated grades. A population estimate is assigned between 21 to 75. This is a R-6 using the Fuld rarity scale.
Both books fail to mention that two types of specimen are available: Intact and Holed. The holed version has the “49” drilled out.
NGC grading standards reflect that holed specimens will be assigned DETAILS grade. The current NGC population is 3 for intact specimens (1 @MS62 and 2@MS63).
The John Raymond So Called Dollar Tabulation reflects that there was no HK-722a identified as being sold through mail bid dealers and auctioneers from the years 1975 through 2000.
Recently, there was an intact HK-722a sold at eBay. The hammer price was $280. I would conservatively grade this medal MS60. However, this is an intact specimen making it even more desirable when comparing it to the current NGC population of 3. Recent eBay sale
I give a thumbs-up to the purchaser who picked up this intact “49” rarity.