Vodafone have said the following about pricing etc.
The HTC One max is a Vodafone exclusive from launch, and will be available on a 24 month Vodafone Red 4G-ready plan from £49 upfront and just £47 each month. That’ll give you the choice of Spotify Premium or Sky Sports Mobile TV access, along with 2GB of data each month. Fancy a #4GBonus? There’s an extra 4GB each month on offer if you sign up before the end of October.
Personally I think this is a bad move, it depends how long the exclusivity period is for. I guess Vodafone paid a few quid for this exclusivity, I just hope it isn’t another nail in HTC’s coffin. Although SIM free customers will still no doubt be ok.
Source – Vodafone Blog