I was a little concerned about cost for fuel as well when I got my R6 and it needed 100 Octane..and actually in the grand scheme of things, the extra fuel costs are not that big of a deal. I spent about $40/day on race gas last year. Which isn't REALLY all that much more than premium pump gas was last year. I'd have spent about $25/day on pump gas at last year's prices.
And a point to consider, race gas has no ethanol. So in your higher performance motor, it may actually be a better way to go for long term.