There is nothing wrong with buying used cams, just be sure to inspect them very carefully before installation and also verify the part # matches what you were told they are. A few weeks ago my friend bought a set of "500-mile HKS 280" cams, they were in perfect condition as stated, but they were either HKS 264 or 272's, not the 280's. I bought my FP4R cams with 1k miles on them and they've been perfect for me.

 

I've had no trouble with the HKS 280's I bought used off a forum member, they were in great shape and have stood up to be beating on em.