You shouldn't need to push that hard on the grinder - those little bits get hot in a hurry and you should be more worried about pausing and dunking them in water to keep them cool. I use a 6" grinder and the only shortcomings I've found are with the junk toolrests found on all these types of grinders.
Homier has cheaper models, by the way (
http://www.homier.com/itemdetail.asp?i=03009&c=11 - 8" 3/4HP for $20).