depends on why if it was because s/he has crap teeth and bucks whenever the teeth are yanked or if the back is sore or the saddle fitting incorrectly then yes... anything else might have to think twice about it
Always ridden them, so doesn't really bother me anymore.
Ruby sometimes has a yipee buck when going into canter out hacking alone. I just ignore her and put my leg on and she doesn't do it again for the rest of the canter.
Like copperpot, I also bought a horse that bucked with me when vieiwng - in fact that is the only time he ever bucked me off!
One thing to consider is re-sale value - although you may see the bucks as acceptable others wont. Not a prob for me as mine is a 'keeper' but something to bear in mind.
The other side of the coin is that 'buckers' often make good jumpers as have a nice active back end!!
If I knew the horse/had a good idea on why, then yes. If not Id walk away. Purely because Ive found in the past when sellers say a harmless buck or rear, they mean vertical belly showing to get you off.
After having had the misfortune to ride a "proper" rearer I would never get on one again. Having 600kg of horse go up and over and land on me was not fun!