When the game first came out we had a fair bit of discussion on it. See for yourself...
Rezolution: First Impressions
I wouldn't worry about the 4.50 pounds for the figures right away. Buy the rules, if you and your friends like them then worry about getting the actual miniatures. In the meantime use your existing models to give the rules a try.
The game designers themselves know these values are not realistic and they do not intend them to replace or invalidate the fluff. So let's get on with our lives and not fixate over the cosmic ramifications of game mechanics which we already know are streamlined for larger forces at the expense of detail.