I could build one cheap, but the commercially available units are nice looking, self-contained, and sanitary. The SunMar runs around $2k, the Biolet is around $1200, the Nature’s Head is under $1k. I actually designed a system for a multi-stall unit using 30 or 55 gallon drums that would use a lever system on the stall doors to rotate and aerate the drums- The system would have cost next to nothing and handled a couple hundred people for a weekend.
To be honest, though I’m willing to spend more to get something that isn’t too different from what we’re all used to. Most of the cheaper systems have a separating system with a bottle for urine or need to be emptied more often. I don’t want to deal with raw waste- I want to shovel out “clean” compost once or twice a year and not have to think about it otherwise. That comes at a cost I’m personally willing to take on.
Also, there’s some awesome stuff on the market right now- This $120 unit could provide enough hot water for an average house- It’s not what it’s advertised for, but we have one, and you wouldn’t believe how much output it has. You can get a small but surprisingly robust plug-n-play solar setup for a couple hundred dollars, and you wouldn’t believe what you can get in 12vdc versions instead of 110vac.
