I really think this is the best idea I've ever had. A brand new one is about $1000. It's an Indian brand, there's also Bajaj, or the considerably more expensive Yamaha. A coworker in Kisumu has one and has put 10,000 miles (kilometers?) on it. It'd take just as long to get places like the Masai Mara, Kisumu, Sipi Falls, Mt. Kenya, Homa Bay, and Kampala on weekends, but it would make the getting there a lot more fun. It would of course be more fun getting there but more tiring, although riding in a matatu (the Nissan minivans into which they cram 20 people) is pretty tiring too.
If it's not raining, I might try and borrow my friends and learn to ride it on the airstrip tomorrow afternoon.