I like running RPGs with minis. Not always... I mean, a great game of Dread, or one of Jim Pinto's Protocol games, or some Apocalypse World and other games I've played, all of these can be fabulous without miniatures, found solely in the mind's eye. However, in general, when running things like fantasy RPGs and campaigns, miniatures can be fun.
I've bought my fair share of minis in the last few years, and actually have painted more than 60 of them, but still have many more in the queue, and sometimes I just feel burnt out on the painting deal. However, being a relatively new miniature painter, I was surprised by what a huge effect the wash has on painting. Wash refers to a paint, normally dark, which is of a fairly watery consistency that is used to give shadows a painted miniature. The first time I painted a mini I had some simple paints, but didn't have a wash, and looking online I found a recipe for do-it-yourself wash (which consisted of dark paint, water, and elmer's glue). It worked, but I quickly moved on to the ones that are put out by the larger mini paint vendors, and haven't regretted it.
All said, buying real miniatures, and of course painting them, can be costly in terms of money, and especially time. But I have found a nice cheat. I've ran into a few cheesy looking plastic kid toys, including little animals, dragons, and such. Although you can use them as is, they tend to be a bit garish... brightly, and poorly, colored. However, applying a dark wash takes it down a notch so that it has a darker, more realistic look. Additionally, the wash allows you to hide what is normally a fairly crappy paint job.
Check out this example of a little plastic dragon, on one side as-is, and on the other side you can see where I applied a dark wash:
Boom, a perfectly usable miniature, for the cost of a few pennies and a few minutes of your time. So far I've done this with a few plastic animals and dinosaurs I've found, with good effect. In at least one case, with a small coiled snake (which would make a great giant snake compared to a 25mm mini) the toy was too brightly colors... In that case I simply painted the snake with a better color and then a wash, and within a few minutes the cheesiness was removed, and I had something that was nefarious looking.