Short answer: Ride for the experience, not to save money.
Long answer:
A bike is a terrible way to save money unless you live in the perfect world. That perfect world would be one in which you cannot crash, have utterly no use for insurance, do not need maintenance, and the weather is good enough for you to ride with just a t-shirt and maybe sunglasses.
Unfortunately crashes happen. Besides insurance and repairs, there’s lost wages and long term disabilities.
Insurance is expensive, especially if you have enough insurance to get you back to as healthy as possible in whatever length of time and care that takes. That may require a combination of vehicle, medical and something to provide for lost wages. The best insurance is improving your attentiveness and skills to prevent a crash. The next best is gear good enough to allow you to walk away without any injuries.
Tires only last 10-15k miles on a bike like the sv650, and as low as 3000 miles for bikes like the Hayabusa and ZX14. Then there’s valve checks and chain tightening. Not a big deal if you can do it yourself, although you’ll almost certainly have to buy a few specialized tools.
Fuel injected bikes in the 600cc range only get around 50 mpg. Bigger bikes drop into the low 30’s. Since this is the only area where you’re likely to save money, what’s the maximum you could save?
Weather can mean having 2-3 different sets of gear for different weather and occasions. You may have a set of textiles for rainy cold weather. Mesh for the summer. Leather for hitting the canyons.
What kind of person are you? I’m a modaholic. For me a bike is cheaper, but that’s because I was throwing $10k at my Corvette every year in go-fast parts. I don’t mod my bike nearly as much, but fortunately the extents to which a bike can be modded is much lower. The bad part is that I keep modding my riding apparal. I have at least 4 sets of leather jackets and pants. A couple sets of textile gear. A couple mesh jackets and pants. 4 sets of boots. 5 pairs of gloves. 4 helmets. This is the kind of shit that makes riding expensive for me. If I was really trying to save money, I would’ve bought a Corolla, but I was only trying to spend less than I was spending on my Corvette.
Anyway, I’d say you should budget $1000 for gear when you first buy the bike. Budget another $500 for tools and parts for the first year. After than you should probably budget another $750 for parts and apparal every year.
I really do not understand people saying not to get a 600cc bike as if you are not an idiot you should have no problem handling it. Just stay in the lower rpm ranges until you get more comfortable. Especially since the suspension on a 600 will handle you better than something like a 250, 500 or even the 650(I was 220 at the time I owned the 650 and the suspension was too soft).