If you can have it confirmed that it's on 9.2 or less and really want an N3DS, I'd say go for it. 9.2 and less N3DSs are becoming more and more scarce, and we may never have another exploitable firmware version; better to get one sooner than later!
Bought it. Cheapest one I could get online was 225$ anyway,without knowing the firmware... In the stores here the cheapest is 420$ ! lol so I think it was okay