I wouldn't say it has to be much more spendy. Have a look at the P2M NGeco, if you buy spider only it's comparable with some Left only units. Also look at Quarq, the Dzero crank is sub £500 on CRC.
If you do decide on hub, expect a new disc version G4 to be out soon (ok maybe early 2019). I think the current G3 requires proprietary rotors.
I wouldn't say it has to be much more spendy. Have a look at the P2M NGeco, if you buy spider only it's comparable with some Left only units. Also look at Quarq, the Dzero crank is sub £500 on CRC.
If you do decide on hub, expect a new disc version G4 to be out soon (ok maybe early 2019). I think the current G3 requires proprietary rotors.