Re: First Bokken
I'd like to offer a counterpoint to the "get what you pay for" school. My first bokken, which I still use, was a ~$10 red oak one. Nice cut, good heavy weight, pretty durable. Especially since my dojo has very low, concrete ceilings (laid out in a grid, so you constantly whack your weapons - bokken and jo anyway - against the dividers if you're average height) I use this one to this day, even though I have a very nice hickory bu jin bokken on my weapons rack back in my dorm room. (I use it for 'open air' practice.)
I recall an article that observed that no bokken can stand up to repeated, heavy contact for very long. I believe Ikeda-sensei remarked that if you're routinely exposing your bokken to such contact, you'll break it sooner or later.
So personally, I say go for a nice cheap red oak weapon from the local martial arts store. Dream about the really spiffy bu jin ones later.