I don't think I'd want to get into printing other people's work as pretty much everyone left in analogue photography is by definition keen and discerning. I know that if anyone else printed my shots I'd be thinking "Could have done with dodging/burning/being lighter/being darker/cropping here", etc.. Renting out a darkroom might be a better bet especially if it's your own that you have anyway and if like mine it's actually only used for a small fraction of the time it could be. Then there's the matter of who do you rent it to and do you trust them not to nick the family silver or (even worse) dip into your stash of paper?