This has been debated about for quite a while, where people give donations in support or the "pay what you can" model.

Unfortunately, many have argued that it (donations or PWYC) doesn't work and people usually pay only when forced to. There is also the claimed psychological issue, where when something is made free or people can pay minimum amounts, that it is devalued or thought as near worthless. On the flip, various people and organizations have claimed that it's possible to use alternate models, depending on how it's done.

Hackers with time on their hands will never pay for anything on a computer they can do themselves, but those with more money than time will pay even if it is open source.