What counts as expensive depends on where you are punting. My usual punting zones, London and West Midlands, have very different pricing.
After punting for awhile, I realised that service is far more important to me than looks. It is too easy to fantasise over some beauty and the wondrous time you are going to have with her, and I think many get suckered into paying more. However, in my experience reality seldom matches the fantasy, in general, the more beautiful the girl, the poorer the service. Beautiful girls don't have to work hard to attract a man, so too many don't have the first clue how to seduce a man. "I'm beautiful, what more do you want?"
Once I have taken my glasses off, who cares what the girl looks like (OK, within reason!). If she can snog like a goodun, she instantly becomes more attractive. And if she knows how to delicately caress a cock, then my eyes will be closed anyway. If she looks good, that is a bonus, but I pay for the service.