I have a personal limit of £15 on digital downloads that I can't remember ever breaking, in fact I rarely buy anything close to that price.
However I think I will make an exception just this once (although it's only a couple of quid difference), they have good reason for wanting to go the distribution route, it's a lot larger in scope than most digital only games and they have built it from the ground up, this interview explains the process of getting it made.
http://metro.co.uk/2014/07/08/oddwo...interview-weve-become-triple-a-indie-4790351/
Assuming they haven't ballsed it up (and it doesn't look/sound like they have) it's worth what they're charging, hell I'd happily pay a lot more for a retail disc if things were different.
After reading that interview, i might pre-order it now. Oddworld universe deserves more games.