One thing I don't like about my plastic regiments is that the figures scatter all over the place at the slightest bump. They're just not quite heavy enough. So I came up with a fairly simple solution that adds weight to the figures without costing an arm and a leg.
I went to a local sporting goods store and bought a 50 lb. bag of lead shot, the kind that people use when refilling shotgun shells. You want some stuff that is pretty darn small, like size 7 1/2 or 8. If you get shot that is too big it will poke out past the bottom of the slotta-bases and you'll have to file it off or something labor-intensive like that. Back when I bought it, I think the bag cost about $20.00. A single bag will probably do several thousand bases. You can pack a lot of lead into 50 pounds. I store mine in a little plastic bin in the closet.
The next thing you need is a whole lot of superglue. It doesn't have to be anything fancy, just a pack of the cheap stuff from the dollar store will be just fine. Scoop up some shot from your container with the base, level it off (over the container so you're not picking up tiny BBs off the ground for the rest of your life), and lay out your bases in some sort of organized fashion. Open up your superglue and squeeze it into the bases, making sure to get a little bit on each bit of shot. Then wait for it to dry. If you flip it over too soon you'll wind up with bases stuck to your table. Today I did 35 bases for about a dollar. This will be heavy enough to keep just about any plastic figure in place, even standard bearers. It will help with metal figures, but I still have metal standard bearers that tip over even with the weighted base.
And that's really about all there is to it. If you're worried about lead poisoning you can paint over the shot and hit the bases with a coat of varnish. Also, you'll be dealing with a huge amount of superglue and the fumes can be overpowering. I'd recommend opening a window or you may experience headaches, nausea, and stinging in your eyes.