Since I am clueless about what a boot should cost (but do know what a boot is, one up on the Doc, lol) and the expected lifespan of one in hours of service, plus what a reasonable cost to break the tire down and install the boot should be. All of these questions are to get an idea so I don't get taken when I call to have someone do the work.
It is no small job to break down & repair a tractor rear tire. Prices here in MO vary by tire size and whether or not an on-site service call is involved. Cheaper if you bring it in. Count on at least an hour at the going labor rate, I think - more for on-site svc call. I paid around $50 for a 14.9x28 tube I think (memory??) a couple of years ago. Smaller should be less. The boot(s) are a minor added cost. If you boot it, you should definitely have a tube in it. Boots are more of a structural patch than an air tight patch, plus the tube will exert pressure against the boot to help hold it. Hard to say how long it will last. Might last quite a while just putzing around with a mower; not so long if doing heavy traction or weight bearing work.