I believe the catalog is the only thing B/F sells on which they actually tack on a small profit margin. They have to stay in biz somehow!
Bob , if you don't get by now that the value of the $20 strictly voluntary donation isn't at all about access to the search function or NBR ( one is a potential perk, the other, well, kind of evens that benefit out...), you likely never will. If you aren't moved to support an expensive-to-maintain & time-consuming-by-it's-hosts site you spend a substantial amount of time participating in, no problem. Really.