If you’re seeing them go for twice as much elsewhere, then it sounds like it might be a good deal. Bear in mind the old adage “if it sounds too good to be true, it probably is.”
It’s possible it’s being sold by someone who had high ideas of amateur radio and wants to rid themselves of a basically brand new radio.
It could be part of an estate sale and the seller did not do sufficient research.
It could be inoperable and the seller is not being forthcoming.
It could be stolen and someone is trying to fence it.
At the end of the day, you have to decide if $350 is worth the risk.