Yeah, they're an excellent way to lose your license. As Emsley says, DRZ400 is a great way to go. Easy to find and you'll probably never lose money on it.
I had an injected CRF450R a few years ago. Great fun on go kart tracks:
Current daily go-to bike in Montana is my Ducati 1100 Hypermotard. I'm actually kinda glad it suffers from a 20% HP deficit at my altitude. Riding it around in California on the back tire was not going to end well.
