I will add that to roadmap as a milestone (http://projects.developer.nokia.com/...anager/roadmap).

That is already in the roadmap. The reason for the current black version is that it should consume less power according to N9 design documents. And another reason was that N950 is black, so the black was looking a lot more stylish ..maybe i will have to support all colors of N9, like pink and blue as well, instead of just black

The testing/unstable version is freeware and you can download it from http://www.jpii.fi/filemanager/testing or you can add the testing repository to your device
after which you should get the latest updates automatically.

Only if you prefer stability and quality over functionality and latest features or if you would like to support the development, you can buy it from Ovi Store in the lowest price point available.