Want to save money? Don't buy a motorcycle
First start with yourself. As a motorcyclist, at the very least, you're going to need a helmet, jacket, gloves and boots. Don't think that's necessary? Look at yourself in the mirror. Look at how squishy you are. The fact that you're 80% water means you're essentially a water balloon. We all know what happens to them. Not convinced? Well try this: strip down naked, run as fast as you can down the road, and throw yourself on the ground. Hurts, doesn't it? All that road rash will sting for a few days (or months if it's at motorcycle speed). Figure on spending around $600 for a decent mid-level protective gear set.
As far as the bikes themselves are concerned, motorcycles require replacement maintenance parts far more frequently than cars do. Neglecting maintenance on your motorcycle is like being a professional sky-diver and forgetting to take care of your parachute, or forgetting to feed your 6000 pound pet tiger, who sleeps in your bed.
While a car usually needs new tires every 30-50 thousand miles, most sporting motorcycles will wear out their tires in around six thousand miles, with ten thousand miles as an extreme before the belts are showing. Name brand tires will normally cost you $300 or more installed, or roughly $.05 per mile.
The drive-chain which connects the transmission to the rear wheel, lasts around 15 thousand miles. The sprockets should be changed when the chain is replaced since the sprockets wear with the chain. The cost of a good name-brand chain and equal quality sprockets will be in the neighborhood of $250, or roughly $.017 per mile.