While looking for a new wheel for our hamster, my wife spotted this cat exercise wheel, which began life (where else) on Kickstarter and is now an object in the stream of commerce.
Judging from the reviews, the first generation of these things had a lot of problems with build-quality and stability, but the new, second gen model looks like it's solved those shakedown problems. There seems to be a lot of Bengal and other purebred owners who've bought these, presumably because they don't want their expensive pets running free through the neighbors' yards. At $250, it's pretty steep, but much cheaper than the pre-Kickstarter cat exercise wheels (an even more niche product!). In addition to helping your cat expend its energy, this also provides the spectacle of a cat on a wheel right there in your own living room, which seems like the kind of thing you might charge admission to in order to recoup some of your investment.