Get your bikes tuned properly to run on the available fuel, as opposed to the typical tune from those dyno jockeys trying to squeeze out the last tenth of a horsepower to impress you with the WOT dyno chart, and you won't need to waste all that money on overpriced cans of toluene. A more conservative tune will solve the problem, and you will be highly unlikely to ever feel the tiny performance difference.
The octane booster industry is a highly misleading and highly profitable business. Most boosters won't raise the actual octane level even one full point, but those misleading names like 101 or 104 or 110 plus or whatever all sell like hotcakes in every convenience store and gas station in this country. Even the more potent mixtures that aren't street legal, like the Lucas stuff, won't increase the real octane rating more than a couple points when used in the prescribed ratio. If you figure the price over a full season to constantly run this stuff, you will see that it wouldn't take very long to spend more than a good tune would cost.
Do yourselves a favor and find a good tuner (not necessarily the kid at your local Harley shop) and tell him you want a conservative tune that will let you run ping free on 89 octane gas. And fill it with 89 octane when you take it in for the tune. Or you could buy racing gas in 55 gallon drums I suppose. You'll need to deal with the damage the lead will do to sensors and stuff, and you'll need to figure out how to carry enough with you for any trip of more than a one tank range, but I'm sure there's a way.
Jerry