My 0.02 as follows:
Take the Motorcycle Safety Foundation course before you get a bike. They provide bike, helmet, instruction, etc on a closed course. It's $50 for a thurs eve and two full saturdays. If you pass, you get your learner's permit. Once you have some exp with a smaller (sub-500cc is a good rule of thumb) then you can get the bigger bike and your full class M license. They teach you not only how to actually ride a bike, but also traffic management strategies....VERY important. If a biker gets nailed by a car it's usually because the driver didn't see you. You must learn to position yourself in traffic to be seen and leave yourself "escape routes" for panic situations. Your state hwy patrol office should have info on the course or check out their website.
As far as looking for a bike,
www.cycletrader.com has the most listings. Also, some dealers will do consignment used bikes. Start small and move up according to your abilities. Don't blow $6000 on a brand-new sportbike...you will wreck it and all that plastic bodywork ain't cheap.
Cheapster made a great point about riding. It is indeed a huge responsibility. You must always be in control and aware of your surroundings. Most people I know who have had bad wrecks were going too fast for their abilities/the conditions and paid the price. I essentially assume drivers never see me and try to anticipate stupid moves on their part. You'll live longer this way.
FWIW- I've had 5 bikes. Chronologically.....a Suzuki GS550E (excellent first bike...not too fast and minimal plastic to crack up), an '84 Honda Interceptor 700 (great bike, now my bro's), '91 Honda Hawk 650, Ducati M900 monster (stolen...dammit), and currently a '96 Triumph Daytona 900 (110hp....whoohoooo!!).
If you wanna go really fast...go to a track day. No cops/cars/pedestrians/deer and lots of hay bales/runoff room if you crash.
Fausto