Lots of people have already suggested stuff...so rather than duplicate, I'll add this: rather than spend $900 on a composting toilet, you can make one yourself with a 5 gallon pail, and a box built around it that supports a toilet seat on top. Put a couple of inches of wood shavings in the bottom, add wood shavings to cover each deposit, and it doesn't stink. I can vouch for this. Then, when the bucket is full, take it to your humanure
compost heap, dump it out, rinse the bucket, and repeat procedure. Put dry carbony stuff on top of the compost box deposit, and it doesn't stink either. Honest. Use cured compost around fruit trees and bushes, if you're squeamish about putting it around, say, spinach. Check out the Humanure Handbook by Joseph Jenkins. Recycle valuable "waste" nutrients, keep waste out of the rivers, and save $$$ on septic pumping. Closing the resource loop--this is permaculture in action.