Some motorcycle engines last a very long time while others are relatively short lived. In general a crotch rocket will not last as long as a touring bike. The guys talking about tires are correct, they don't last long and are expensive. Chains and sprockets are another wear item. You might consider looking for a good used liquid cooled shaft drive bike like an old Gold Wing or the mid sized CX500.
I drive a CX500 (Honda) with about 100,000 miles on it so far and I don't see any reason it won't go another 100,000 miles. Last year I pulled the heads off, checked the rings, pistons, bearings, etc., all of which were perfect. Ring end gap was within new specs. Oil change interval is 7,500 miles, no chain. The bike will cruise easily at 80 all day long.
You say you are going to use cheap tires on the bike, but I would check what ever stock size is on it and make sure they make cheaper tires in that size. The rims may be wide enough that they only make sport tires for it.
With that many miles a day, taking care of a chain would be a pain. You'd need to lube it a couple times a week to keep from wearing it out and then have it throw the lube all over you. I was actually thinking an old CX500 would be a good commuter. It has a large gas tank that you probably would only have to fill it once a day or day and a half. Being a twin, it would get metter mpg, and you could get touring tires on it that would probably make 20K or better miles.
Just thought i'd point this out, but I've noticed if I drive my bike like a crotch rocket, things get very akward. What I'm tryign to say is, your manliness will be very uncomfortable by the time you get to work, or home. Just something you might want to think about.
I almost got a yamaha virago 250 this week. It looks good, gets 85mpg and is like $3500. I decided that I would have more fun with something like a dual purpose suzuki dr650 so I will be getting one of them one of these days when I get a good deal on it.
http://needabike.com/numbers.html this site is great to give you an idea of weight, acceleration, and top speeds. Doesn't give mileage though is the only thing missing.
Suggestions #1 & #2: Find a job closer to home - or move!
The 'commute' that so many people in CA deal with every single day is just unfathomable to me. On a slow day, it takes me 20 minutes by bicycle, less than 10 when I'm feeling energetic.
That said, I bought a KLR-650 a couple of years ago with 92,000 miles on it and it was still running strong until I sold it last year. Maintenance cost on them is low and you can expect mid-50 mpg most of the time. Considering a new one goes for about $5k, that's allot of bang for the buck - but you won't be breaking much more than 80-85 mph on one unless you like getting tossed around allot by the wind. (Though they will do about 100 mph if you dare.)
For a crotch rocket styled bike, that looks to have more upright seating, so it might be bearable, altho it also puts strain on yoru neck and back to be bent over low like that, so if you are buying it new, they should let you take it for a test drive first, think about these things as you are riding it.
Motorcycles have improved a great deal over the years, you no longer have to do an over haul at 10,000 miles, it's hard to find one with a carburator, so all the problems that go along with carburators are gone, a very weak point as most cycles tend to sit for months or years at a time, and fuel drys up.
Water cooled engines tend to last longer as well as the engine temp tends to stay more stable and it lessens the chance of having a hot spot, it also helps keep the oil from braking down as fast.
A good O-ring chain or X-Ring chan, cross sections of the o-ring is an x shape insted of solid round chunk of rubber to make up the ring giving more points of contact to seal lube inside the chain, and a good o-ring chain should last many years, normal is 20-30 times the normal life of a non o-ring chain, so maybe at 50,000 miles you should check the chain for wear.
rear tire is what is going to wear fastest, it's a 180/55-17 off the top of my head I don't know of there is a touring tire in that size, but if there is I would sugest you get it, Contenental, or Perreli, or something that clames high milage, motorcycle tires are designed to be sticky, sport bike tires are even softer so they wear even faster, touring tires are designed for going down the highway in a straight line, and also designed at times for a bit of rain, not for hard cornering.
I've seen air cooled, carburated motorcycle engines that lasted 60,000-80,000 miles befor needing a compleat overhaul, my current motorcycle has 20,000 on it's little air cooled single cylinder 125cc engine, and yes, it has some wear, but it also spends most of it's time between 8,000 and 10,000rpm a sprot bike might be closer to 5,000-6,000 rpm, on your test ride check and see how it runs at lower rpm, some sport bikes will not run right unless they are reved up, anyway a water cooled fuel injected engine should last a long time, and after you've broken it in and changed the oil once it might be worth finding a motorcycle compatible synthetic (never put a synthetic with friction modifyers in or you will destroy your wet clutch), and do the sugested matence on it and your engine should last 100,000+ miles.
If you take excellent care of the engine you will get 100,000+ miles out of it, same for the rest of the bike except for normal wear items. These engines are built to last under some pretty high stress situations.
However with a long commute, consider your comfort. A new Kawasaki Concours (not the 1400) will sell for right about 7000 or less, is comfortable, fun and will net you right about the same mileage. Plus you may ride it more because it fits your riding style (pattern) better.
The Kawasaki is one (I'm biased) but there are other sport-touring bikes that will fit the bill just fine for long commutes. It is a great way to go! Enjoy!
You may want to look at an older bike and save some money. The liquid cooled engine last much longer than the air cooled engines.
My 87 Kawasaki 305 gets 60 mpg. The belt drive is nice and low maint. (until the $100 belt breaks). Shaft drive will rob some efficiency. It cost $400 and I put new tires and a battery in. For $550 it runs like a new bike (it has 12K miles) and is a great gassaver.
I have been on the interstate once and its a little light to be in amongst semi's (you get tossed around by the wind).