I'm glad you were able to visit WMG's Living Lab & Learning Center! The 5 gallon bucket system is the cheapest and easiest CT system to build. Catlow and I used one at home for two years. However, I greatly prefer the 55 gallon drum CTs for ease of composting and convenience.
Here is a comparison of 5 gal to 55 gal:
Cost: 5 gal is best, but 55 gal is still much less expensive than a commercial variety
Composting Management: 55 gal is much easier because it is easy to turn the pile with a compost crank and the large bin keeps more consistent moisture
Routine Cleaning: 55 gal is much easier, because you only have to clean the seat. You have to clean the 5 gal bucket every time you empty it (my husband hated doing this!). And with urine in the bucket and can get really stinky.
Urine Diversion: 55 gal is much easier to set up a set urine diversion within the toilet system. You can then directly use the urine in the landscape - to fully utilize its nitrogen content. When urine is mixed with everything else in the 5 gal bucket system, you loose it's fertilizer potential.
We turn around finished compost in 4 months with the 55 gallon drum CT.
You can definitely install CTs in your house. Catlow's Dad has a 5 gallon bucket CT system indoors and we just built an indoor 55 gallon drum CT in our indoor bathroom this winter. We built a wooden box that contains the large barrel. Fortunately, we built this toilet while remodeling our bathroom, and we had our contractor build the vent and urine diversion piping into the walls, so they are not exposed. Our urine diversion pipe taps into our kitchen resource drain to irrigate and fertilize a pomegranate and mesquite tree. We will just have two barrels for the indoor toilet, and the aging barrel will be stored outside. We'll be sharing photos through our website soon!