Peter, so far there's not one teeny, tiny aspect of this trip that has been cheap. Renting a helicopter would be cheap by comparison to some of the things we've decided to do! (God bless her!)
I'll admit it, and it may shock you, but I do occassionally like to partake in a little liquid refreshment. The problem with hiring a car, which is indeed most sensible, is that I would have to drive it. In which case we'd hire a car, then go everywhere by taxi anyway.
'Tis a conundrum, to be sure.