I personally wouldn't buy a used Harley if it has averaged more than 10K miles per year and/or has a lot of "performance" upgrades because that tells me the bike was probably ridden hard.

 

like the other guys mentioned, these newer twin cam motors are really durable, and can go for a lot of miles before anything needs to be addressed. figure out which year you want, because there were many changes to the twin cam motor through the years. i feel that an 08 or newer has some real goodies, but if you can get into an 09 then that'd even be better because of the new frame. it depends on price obviously, but you can find the right bike if you take your time. you are shopping for one at the right time of the year when many parts of the country are too cold to ride. good luck.