I believe that Meguiars is worth the money you pay. It can be a bit of an outlay intially but I find that you will get a fair bit out of each bottle.
I use their wash gel, fine cut cleaner, glaze, canuba (spelling?!) wax, plastic and vinyl conditioner (inside) and the long lasting tyre stuff.
Obviously the cut and polish stuff lasts longer because I dont use it all the time but its prolly good for about 6 jobs. The tyre stuff has gone longer than the suggested number of uses on the bottle and the plastic cleaner is waayyy better than Armoural IMHO.