I bought a trade paperback for $19.95 last week -- but it was an anthology of
four novels by a New York Times best-selling author (R. A. Salvatore). And I had a coupon.
OTOH I have seen a lot of trade paperbacks starting at $15, from both big and small publishers. The pricing depends on the niche. I think $14 used to be more typical for some trade paperbacks, but prices are creeping up. Higher prices are common for very thick books or for some types of nonfiction. (For example, in-depth true crime, biographies of Wild West personages, etc.)
These days, in most cases, I don't want to take a chance on that kind of money, even if I
know the author or know I can trust the publisher. When both the publisher and the author are new to me, I'm not going to buy it. I might look the book up and look for trusted reviews, but I'm just as likely to put it down with a little "Eek!" There are too many other books to spend my money on (not to mention little things like food and clothing).