You've made an astute observation, even for an experienced chipper, so you are off to a good start as a new chip collector. Asking the right questions is always the place to start. Welcome.

I don't know the reason for the difference in value, but can offer some general information, which you may already have figured out. The $100 Harolds Club chip you refer to is the last rack chip used by Harolds before they closed. This CIC (coin in center) chip was plentiful on the tables at the time, and the lower denominations of this chip ($1's and $5's) are pretty easy to obtain, though at a premium over face value now. If one of these $100's was obtained when the club was still open, the collector wouldn't want to sell it for less than face value, and over time, it should increase in value due to the time-value of money invested in the chip, plus the fact that the club is closed and it's not available off the tables any more. While there aren't too many $100+ denomination collectors out there, the chip should hold a value above face UNLESS...

Sometimes chips from closed casinos are not destroyed after the redemption period has passed, but instead, find their way onto the collector market. In this case, chips will sell for below face value (sometimes only a few dollars per chip, regardless of face value). The implication of a $100 Harolds Club chip at $40 to $60 would mean that some were not destroyed. Since there aren't that many high-value collectors, it doesn't take many $100 chips to satisfy the "core" demand for these chips -- probably less than a box.

I suspect that the TCR authors are basing the chip's value on a cost-plus basis; and that the other guide knows of a supply that has become available after the club closed (either that, or it's a typo or mistake). Perhaps someone familiar with this specific chip will add some concrete info. I've just given the general explanation of how chips may sell for less than face value.