I think I would ask the cousin if it is okay with them, that you would like your kids to have a copy. If they shared it with you, I doubt they will have a problem with sharing with your children.
I also agree that this is an expensive hobby, I have been doing genealogy for years and have had a lot of fun with it. Shared my information with several "found" family members, until I started noticing they were publishing without paying attention to dates (entering incorrect data on the ancestry website)