Not much of a help, but a guy local to me is selling a GT i-drive 2 from the same year at £220 and has had zero interest. His doesn't look as nice as your one though.
I've used Microshift Bona in the past and it was excellent although the front shifting was tricky to set up right, I've also used Sensah for a couple of years now and like it although I'm now trying out Ltwoo which works well so far, although I prefer the Sensah shifting so far.