This offer here would be something I'd look into, except learning it hurts the library more than expected is a downer.
Which is likely an incentive for libraries to not expose those costs on a per-request basis. As thebitstick mentioned here[1], libraries want to encourage usage. Overall usage volume has already been budgeted for, so the variances between one request and another for a typical patron won't materially impact the overall capacity of a library from serving their patrons. Inversely, if exposing the individual request costs disincentive enough conscientious patrons from making those requests, it makes it more difficult for the library to justify the service at all and could result in the loss of budget to continue covering it. Which ends up being a net loss of access for those patrons which do not have the means to access it elsewhere and were reliant on the library for it.