I wouldnt recommend that, mainly due to the fact it is untruthful. I personally will not sell used technology for more than what it is worth on craigslist, as i feel doing so is basically preying upon the unknowing.
He Isn't lieing, he is just enchancing the truth a little.
He hardly got a full life out of the system, he simply thoroughly tested it. Everything may aswell be new, a few months to a component is nothing, the lifespan of components fluctuates by more than that, and to know it has been tested and working and to know what it is capable of, that is a good thing for the seller.
And he
did build it, so that is labour costs going into that, not just parts cost. I know if I built a system and sold it I wouldn't sell for what I payed for it, I'm not running a charity, I would have built the system to make money, I put time and effort into that. Obviously if I payed £1000 for a system 10 years ago and I built it myself, I'm not going to sell it for just over that, it is outdated and heavily used, but a new, modern system, different story.
To OP: good luck with the sale