At the two places I use I get charged either £15 or £20 to have a tyre off re fitted and balanced, thats taking it there myself loose. I got caught short with a puncture and went to a kwikfit who charged me £25 last month, would have been more but I took the wheel off myself in the car park. With this latest set of wheels I just bought and the puncture I have spent around £100 just having tyres swapped over and resealed and will need 2 new tyres on the GT4 soon. When you look at some of the machines on ebay for around £100 it would work out cheaper in the long run, not necessarily easier and like you say, levering it off the rim is likely to fck them right up...