Microscopes are like pieces of string. In general the more you pay the better the lens quality and microscope. But have a look at Brunel http://www.brunelmicroscopes.co.uk/index.html
They do several entry level scopes that are more than acceptable plus all the kit and stains you need to look at pollen.
Pollen Identification for Beekeepers by Rex Sayer is as near a bible as you can get.
But be warned it's not easy....lots are simply round and many are sausage shaped....trying to distinguish what is what is not always easy....