Donations are a necessity for any community enterprise, churches included. No donations means there will be no buildings, no maintenance, no priests or parsons, no charitable work.
In the religion industry the standard used is the tithe which, we all know, is around 10%. It's a pretty hefty tax for people on low wages to hand over but, since they believe in all that stuff, and since they want to meet their obligation, they ante up, even though they may have to do without in other areas. What the heck? God will provide, won't he? Yeah, right.
The problem with tithing is that it doesn't stop there and the spruikers (in the US you call them sideshow barkers) in the pulpits are adept at milking their congregations for more. How often have you heard something like, "God is going to work a miracle in this place and he wants YOU to be a part of it." And another, Yeah, right!
One of the problems with this sort of thing is that it's so often the people who can least afford to part with their money who are the most generous. The wealthier members of the congregation didn't get that way by being overly generous.
So is it appropriate? I don't think so. If God wants money let him work for it like everybody else.