When I lived outside of Washington DC I was a FONZ. (That stands for Friend of the National Zoo.) Being a FONZ gained you certain privileges, one of which was an inside scoop on what was happening at the zoo. That's how I found out about "Zoo Doo." Zoo Doo was probably the most "natural" solution to a difficult problem – namely what to do with all the poo. They had it made into garden art. You could purchase poo pottery, place it in your garden, and have a somewhat attractive, naturally decomposing source of nutrients for your plants and soil. A win-win as far as I could tell. I'm not sure if the National Zoo is still involved in this program. I wasn't able to find any information on it. But, I did find a company in New Zealand that must have latched on to the same idea. They sell Endangered Feces statuary. Brilliant stuff.
If you live near a zoo, it may be worth contacting them regarding their disposal of waste. They've obviously got the supply, you could make the demand. The Woodland Park Zoo outside of Seattle, WA offers up Elephant dung by the gallon.
Of course, if you'd rather have a more lasting piece of statuary that doesn't have its own special aroma; you may want to check out the Jungle Stores Lawn and Garden area.