I'd look around and call some smaller tree guys, and get a quote. If there happens to be one near your neighbourhood, you can ask and a lot of times these guys will do it cheap on a whim for cash if they're already there anyways...
You can also look around the old fashioned way for business cards on cork boards and some guys even post their number around major traffic areas on signs, probably illegally. I suspect you can get it done for quite a bit cheaper than $120...
And while I don't know the size of your "smallish" stumps, the unit you rent will likely be a gas-powered unit such as a Vermeer SC252 and not very powerful if you have to get roots. A smaller diesel unit like an SC372 (or equivalent) would be preferable, but those will be a little harder to find as a rental...