I know what you mean Germinator. We have about 90 allotments on our site, the number who arrive on bikes and on foot are getting less and less. It just means you don't get the chance to chat to them and find out their names. It's a shame when you have to say "that gent/lady with the big 4x4 has some nice peas" instead of knowing his/her name. :)
By the way our allotment costs have just risen, we pay £50. It includes water rate, which varies depending how much water is used.