If it's worth $50, give it to early-adopters/supporters for 50%, because unlike buying something for $50, they don't get it now (and there's many a ways for a project to not deliver). In this promotion phase, it's good to have exciting specials. (e.g. Notch's 50% beta Minecraft) Marginal cost of software is zero, more users = more evangelists etc.

Saying "license" looks non-free. I guess it includes the closed-source plug-ins (?). Good to clarify.