Aviation fuel isn't likley the best choice, regardless of price. You're not doing yourself any favors using a fuel designed to run in an engine at tens of thousands of feet altitude. You're familiar with fuel volatility curves? Such distillation curves are
designed for specific reasons..and specific applications.
The octane number doesn't really mean anything when you're comparing two completely different fuels, either. I'm saying a high octane number doesn't equate to 'more' anything...not more power, not more HP, etc. Running a higher octane than your engine requires is a waste of time..and likely money.
Here's some good reading:
http://dirtrider.net/forums3/showthread.php?s=&threadid=5277&perpage=20&display=&pagenumber=1
Certainly you can run whatever you like in your bike. Might as well make an informed decision, though. Some places (some countries in South America by report) have 25% alcohol blended fuels. I guess if THAT junk is your pump gas option, 'avgas' (whatever that term means in your case) may BE the best choice!
Cheers!