The cost of buying a new pair of quality walking boots can be high, therefore having them repaired with a quality sole makes good sense.
You should be aware that a cheap, brand new pair of walking boots can often be bought for less than a quality repair, however they are often inferior quality and many find them uncomfortable.
A complete resole repair can be a laborious process for the cobbler so the price often reflects this. Your boots current sole is patched or removed prepped and glued, and after the resoling process the boots are finished by hand, and then usually conditioned for waterproofing. The price guide quoted here is for the entire units. However it is often possible to get the heel or the sole repaired without replacing the entire unit. These repairs can be more cost effective and just as durable, but perhaps not quite as aesthetically pleasing.