Just a bit more info on these "HNO" chips, as Sheldon's question piqued my curiosity.

According to a Chipguide note, the Frontier LV "dig" that discovered the Sands HNO chips (damaged / discolored in various ways), happened in 2007.

The Campiglia & Wells 3rd edition was published in 2005 (pre-dig). Info on the HNO chips in this guide: HNO = 12th issue.
$5 was rated an R-7 (16-30 known); $25 was rated an R-9 (4-7 known); and $100 was rated an R-10 (2-3 known).

Even if those census numbers were somewhat low, there were pre-dig chips in existence.

IMO, there are few if any "dig" chips that are in as good a condition as those pre-dig chips that were never buried in concrete for many years. The pre-dig chips should (and usually do) command a meaningful premium vs. dig chips.