What about implementing USER PAYS!
(Many modern not-for-profit activities are considered naive or not viable if they cannot pay their way.
Traditional User Pays Would Cause Major Pain Amongst Those this is Intended to Benefit.
Not-for-profit Scientific Databases/Publications should be maximising its distribution and finding ways to do this. Again, the rationale behind this is that scientists cannot be participating in meaningful science and education if they do not have the resources to determine where existing knowledge stops and the unknown starts. Thus it would seem that geographical boundaries determining who can afford to obtain up to date reference information.
Medical doctors credo - "Do no harm".
Trying to charge production costs of $20 to the target audience could do serious "financial" harm. Rather than try doing the most good (we are extracting money here!), equalise and minimise the harm/financial pain.
Whatever strategy is considered, it has to cover production and development costs.