Not a UK supplier, but a United States one: http://montorc.com Just spent over $800 on these: http://montorc.com/avrotolift3520400kv.aspx Got a message today, a few hours after payment, saying they've been shipped so will see how long it takes. Will probably get stung by customs, always do from US, but there's only one place selling these in the UK and I never heard of them and they're a lot more expensive anyway.
I must admit I'm really looking forward to seeing them. Keep checking shipping. I'm betting they get to the UK really fast, then spend a week in customs before coming to York. Currently: Processed Through Sort Facility Your item was processed through our ISC CHICAGO IL (USPS) facility on November 6, 2013 at 4:28 pm. The item is currently in transit to the destination.
Arrived! And for size comparison, Avroto LIFT Series AVL3520 400 with Torxpower (T-Motor, Tiger Motor) MC3536 Pro.