And how many miles did you ride in October? I bet your $$/mile is a bit above the $.50 or so it costs to drive a car.
Btw, you can get an under saddle bag for a lot less than $20. Maybe something like $7-8 on sale at performance.
I would estimate that I rode maybe 100-150 miles in October, so WAY above $0.50 per mile. I hope to increase my distance per outing from the LOW 6 or 7 miles I average now to maybe double that or more. That should help with that ratio but it will still be a while before/if I ever get lower than $0.50 per mile.
As for the bag, I was just throwing our an estimate. Just as there are $5 bags out there, there are also $100+ bags out there.