At least around here $150 is what you would pay for that model grill itself without the cart (22" with the easy clean set up and lid holder). That exact one you have is $350 and the one I have that's the same but with a smaller table and no charcoal bin is $250. The price he quoted you seems like a good deal if that's the model you really want. If you just want the grill itself you can get a new one for that price. They're all good though, Weber definitely knows what they're doing.
I actually got mine as a gift for 25 years of service at my job. Perfect timing because I was going to buy one anyway.Just used it the other day to make some really dry chicken. All the equipment in the world doesn't cover my incompetence sometimes.