My advice is go for a sit-up-and-beg style bike. The likes of the Honda CB400. My first bike was a Kawasaki GPZ500s, also known as the ER5, good bike, parallel twin with enough power to pull a decent wheelie but cheap enough and light enough to fix once its been down.
Accept you are going to go down, buy the best protection you can afford, not just a helmet and jacket but your going to want trousers (don't just wear jeans), boots, very good gloves and then your going to want wet weather gear too. Trust me its uncomfortable riding when your soaked through, and the trickle of water down your gut to your knackers confirms how wet you are.
Another thing to consider is security, your going to need a disc lock and a good chain, your going to forget about the disc lock at least once - we all do.
As above don't treat riding as a way of cheap way of transport as its far from it especially to get set up.
I don't ride now as I have 2 sons under 6 years of age, I want them to have a dad until they are at least teenagers.
Folk aren't trying to scare you but you have to ride defensive and if you get complacent that will be when Doris pulls out on you, I had a number of close calls and luckily for me only 1 hit that was so minor it only left the molten mess of the car bumper that pulled into me on my left exhaust pipe, I didn't go down.
I passed my UK Mod 1 bike license at 21 years of age and rode for approx 10 years before selling up, I rode through 3 winters and its hard work especially on a 1300cc air cooled bike like my Yamaha XJR1300SP. At 0 Degree's Celsius the wind chill on your fingers at 30mph is -16Degrees, hence the remark about good gloves.
I've also ridden in the USA, LA to be exact and its was an interesting experience, City centres where very defensive riding, along the coast and into the mountains was more relaxed.
Now the good bits about riding are brilliant, freedom and excitement to name two feelings, also a sense of community and comradery amongst fellow bikers is stronger than RC's. The connection you have with your bike knowing there is no aids, its all on you and your riding ability.
My opinion is buy a bike to go riding on evenings and weekends, gain confidence and ability before riding to commute. If your wanting to save money on your commute buy a small engine'd compact car that used purely for the commute, it'll be something you can use even in bad weather and cost less than a bike in both maintenance and medical bills.