Sorry for posting on such an old thread, but I was searching old threads, and I had an idea when I read this one.
Maybe the trick to limiting bikes is what, in motorsports, is called a “claiming rule.” To prevent teams from using financial “WMDs,” you have a rule that anyone can buy the bike that wins a race for a fixed amount of money, say, 3-4,000 euros. Not a replica, the actual bike that won. Better yet, the team has to sell all of their bikes they used in that race. That way, teams won’t spend too much money on “unobtainium,” because it might be bought out from under them for pennies on the dollar, and if they use expensive technology, the other teams can buy it away from them. It’s not a perfect system, but some sort of concept like this has been very useful for preventing unobtaium in motorsports, or at least distributing it cost-effectively (Honda has sometimes used super-exotic suspensions in production bike road racing, for a marquis race like the Daytona supersport race, but then a privateer team can buy it and race it at the next race).