There was a post about donating to help improve the site.
I think this is a good idea to help improve the service to the site as increasing the monthly cost may deter other people from joining. So far I have had good results.
Having a dedicated donate button available can make it easier for those who wish to donate the ability to do so. So long as we know how the donations will be used such as development of the website and/or tracking more tables, I think members will be open to the idea.