well 20min of driving and some weekend driving you are not going to like a crotch rocket for long. the guys that try to go on long rides with us cramp up after awhile. The busa is a nice bike but for the street a 600-750 has plenty of snap and power, my 1200 bandit which has the older gsxr motor but built for mid range power flies plenty for me although it has a pipe, stage 1 jet kit and tune but still you get the point. a busa would still kill me but a regular street with traffic he cant lose me or a 750.
Make sure you save some cash to get some gear. I have been riding for over 10yrs and never ride w/o atleast boots, gloves and my helmet. 99% of the time I have on my joe rocket pants and jacket. the drivers keep getting worse and they talk on the cell phones and need to get every where in a hurry. here is a place to get great deals on gear, they have cust reviews on stuff
http://www.motorcycle-superstore.com/
also I'm a suzuki, yamaha fan and I like kawasaki too. here are some good choices of bikes
suzuki
Bandit gsf 600 or 1200 come naked or s model has fairing, great motor no problems have had mine new since 2001.
suzuki sv models, if you really want crotch gsxr 600 or 750's are great bikes!!
Yamaha fz6 great little bike right here or the bigger fz1 & the yzf
Kawasaki zzr600, ninja 650 or 500r, the smaller ninjas sit more upright and look really cool, now don't discount the 500, I have riden the 500 and this thing moves out and is a stout bike a 2008 msrp's for $5,099 and do some haggling and you can get a brand new bike for want you want to spend. these bikes have great resale because people buy them for starter bikes

. that's what my buddy did( the one I rode) he bought his rode it for 2yrs and resold it for almost what he paid.
anyways best of luck to you. and be safe man.