I bought my bike in Feb '09 with 3,300 miles. I had wanted a bike for years but couldn't justify the cost of such a luxury/toy. I did the math and figured out a bike would pay for itself in what I would save in gas with a 50 mile round-trip commute everyday.
At 8,500 miles, after replacing the tires and getting shocked by the price of an oil change (which I now do myself), I calculated my cost of ownership. At $189 per month P&I, $35 per month insurance and figuring in the tires and oil, plus fuel used in that 5,200 miles, I came out $90 cheaper than the cost of operating my paid for F150. The costs for the pickup were for fuel and oil only. My huge cost was the tires, but I replaced them with Michelin Power Pilot 2TC tires that have awesome grip in the twisties and still have half tread with 10,000 miles on them. And I now have a bike, which I didn't before.