I don't think this is it. If I remember correctly it was something like "An Education for $20" and it was written as an argument in favor of paperbacks and how they made many things affordable that, previously, had not been. I don't know if it was on this site, of course it seems familiar to me because I've seen it many times. Paul is looking. This list seems to have too much fiction and I think it's just a list out of Education of a Wandering Man

The full list (1000x more that $20 even back in the day) is here -- https://www.louislamourslosttreasures.com/books_read/index.htm

If you all haven't poked around in the Lost Treasures site you are missing a lot of weird details of LL's work. It's worth taking a look.