It always feels like open source enthusiasts would never pay for something themselves, but expect that their boss will for some reason. What would your boss get by paying that he/she isn't already getting for free?
It would help if the projects had some option to purchase a license or subscription, even if the application is open source. Lots of employees have a company credit card and the authorization to use it for small productivity purchases. But it would have to be a business expense that is easy to file, not a donation.