At the University of Toronto Press website today, the top item under the "Current Bestsellers" heading is the Oneida-English/English-Oneida Dictionary by Karin E. Michelson and Mercy A. Doxtator.
I would guess that, in the ways we usually talk about bestsellers, the market for this work is actually fairly limited. As the book notes say:
Oneida is an endangered Iroquoian language spoken fluently by fewer than 250 people. This is the first comprehensive dictionary of the Oneida language as used in Ontario, where most of the surviving speakers reside.So I'm not sure what the bestseller listing says about scholarly publishing or about what makes a bestseller in scholarly publishing these days. But I do think it is wonderful that such a work of scholarship exists, and can be published, and that someone somewhere considers it a bestselling work, whatever its Amazon ranking, or whatever, may be.
The poet Robert Bringhurst has said that every North American poet should learn enough of one indigenous language to translate some of its literature into English. He didn't say historians should too, but it's kinda the same thing.