I'd pay nothing, and host it on GitHub. In fact I, and many others do.

The OP said "Let's say I wan't to host it myself". So his pricing is right.

And the new appstore doesn't stop anyone from hosting their OSS on github - even for Macs. The appstore is for the average user; github is for the better than average programmer.

D'oh, I read wan't as don't want because of the superfluous '.

you'd also be alienating a large number of non-technical users who just want to see a large download button.

If your users are the "compile from source" crowd, I agree the Mac App Store has no benefit to you.