I don't want to sound contrary, but I'm going to put in my two-pence worth...
I always hated classes- if anything they demotivated me. I really do appreciate that the 2 seperate experiences I had with groups must be very rare, but they would just get me angry- people would just use them as moaning sessions about how hard it was and how they couldn't do it and it wasn't there fault so I found it increasingly difficult to make the effort to stay as I left feeling so de-motivated.
I recognised though that I needed to 'commit' to it, so I joined bodyOptimise (SW online) which is the perfect compromise for me, as i work away, hated classes, but still wanted all the SW resources and to make a financial commitment to ensure I stuck to it- I pay in advance so it is harder for me to fall off the wagon and have all the support I require straight from the horses mouth (and not re-interpreted by a consultant who may give a different story to the next)
But, I completely understand that this is a personal choice- I still absolutely agree that paying £4.50 just to weigh-in may eventually lead to you dropping it, just wanted to give an alternative view point
Good luck in whatever you do