I discover somewhat to my surprise, that
new designs of milkfloat are still being developed[a].
Also,
from the same site, "A serviceable, second-hand milk float, with half-decent batteries, will set you back around 500 pounds. A float in good condition with good batteries may cost more than twice that."
Is that all?
[a] And I thought they were going to ship them to Kathmandu to solve pollution problems, but apparently the drive system is rather old-fashioned.