I bought my first motorcycle at 18. It was this 1986 Yamaha Radian (YX600S). Bought in June 2007, three months after taking MSF course and getting my motorcycle endorsement. I originally wanted a Ninja 250/500 but they command too much of a premium for anything in decent condition. I paid $900 for the Radian with 16k miles and a slipping clutch. A new clutch cable helped a ton, and acceleration was all a beginner needed with about 70 horsepower. Also had to put a little bit of money into spark plugs, oil, and a new rear tire, but the money I put into it still was way under $1500. Sold for $1500 in summer 2008 during the really high gas prices. Put almost 4k miles on it in about 4 months of riding.