...they have a few available for less (and the one nearest to the $60 ballpark actually costs almost $85).
The implication I presume of a cheaper chip is less accuracy, though how sizable a problem might that be?
From what I gather on the datasheet, even a standard AD538 has an "Error of reading" of only +/-0.25%. Admittedly though, if you wana talk percentages, I'm not 100% sure what that implies.