If you don't want to put the kids off walking for life, then make sure their boots are easy on the feet. These little brown boots score big in that regard, and our junior reviewer has been keen to wear them everywhere from summits to school.
These are great boots, we discovered them after our eldest got her feet soaked once too often whilst wearing fabric boots. Being out in the hills with wet feet is no fun at all, especially if you're out camping for a couple of days. She's now onto her second pair with the first pair being handed down to her sister and still going strong. Pricey but, as you say, a good investment if you can hand them down.