As far as I know, bike warranty are only for original owners....so I don't think that it matters whether it comes with warranty or not. But if that owner has the receipts, at least you know the bike was not stolen.

It sounds like a fair price. But, I guess if you already have a MTB, I don't know what you would be using this for since you are trying to save up since "you are a student".

I don't own this bike, but a lot of TE members have liked this bike in the past as a starter bike/commuter bike.