Hi flametenebra,
7digital.com does indeed sell tracks at 320 KPS, while indiestore is a service of 7digital it does not as yet sell tracks at this quality.
We see this as a key feature for users such as yourself and we are looking to get high quality tracks in place where the indiestore manager has uploaded them.
We recommend that you still upload tracks in the highest quality that you have so that you can take advange of this new feature when it becomes available.
Andrew.