I had to go to Lowes this evening, so I checked. My Lowes has metric machine bolts down to M3, in 3 lengths. I think most MTH bolts are M2.
rtr12: When you need small parts, another solution is to e-mail one of the techs, like GRJ or GGG, for their shipping might be less. I don't know what the webmaster's reaction would be to posting requests to buy parts. That could be a whole new forum, but then the techs would be trying to bid against each other and that probably wouldn't be healthy for them.