Heather - I initially wrote a long reply with my perspective on the situation, (while I don't have the electronics knowledge to design crossovers, I do design and build cabinets), but then decided it boils down to the fact that researching, designing, and testing things takes substantially more time that most people realize, and if you're doing it primarily for others' benefit, it's only fair to expect some kind of payback, otherwise, 'might as well just go fishin', or do a regular job that likely pays more in return...
If I'm doing a job that also includes the resulting "product" for me, then I'm definitely willing to absorb part of the expense, (as I think most others here do also). But I still like to think the rest gets spread around fairly, as I'm sure others do.
'Only speaking for myself here - others may have different ideas...
John