I have to agree with others here - you're much better off with external mics, even cheap ones, versus even the best internals. One reason is that internals are often X/Y, which is very rarely the best choice for capturing any kind of natural stereo image. Alternately, you get internal omnis that are much too close together. Either way, you get a mostly mono recording unless you're in the exact position for that arrangement to work (which is doubtful). Any kind of externals allow you so much more flexibility with placement so you actually have the opportunity to get the best sound, instead of being locked in to the highly compromised setup you get with internals.
If you need small, something like the Sony M10, a battery box, and and the AT853 wired for plug in power are a great combo. Darktrain frequently has them for sale in a variety of configurations. For your drum circle, a pair of omnis would be good as suggest mentioned, either spaced 40-60cm in a stand or HRTF. Check out the Naiant X-X, great bang for the buck, and Jon can set then up any way you need.
If you can afford to go with something a little bit larger, you'd be hard pressed to do better than the Tascam DR-70D, usually around $250. The big advantage is 4 XLR inputs, allowing you the flexibility of 4 channel recording down the road. Gutbucket can share all kinds of ideas for interesting multi-mic surround techniques he uses, and while you may not want or need that right now, it's nice to have the option later.