New 3DS is better in every aspect plus like you said. It's cheaper. I hope that seller is legit though. Good luck on that one.
Not in every aspect though, the 3DS Audio Chip of the N3DS is arguably worse than the original 3DS, this was a given since the 3DS XL had a Nerfed Audio Chip compared to the original, and the N3DS practically reused the same nerfed chip, so, for audiophiles like me, the O3DS is better in that regard, and don't forget the fact that the N3DS can't surpass Emunand over 9.5, and as such all the games have to be played firmware spoofed.
But as a choice, yeah, go for it, New 3DS consoles in 9.0 and 9.2 are getting rare as time goes on, so, pick that choice and enjoy what you can from it.