We outgrew the bo staffs before they needed to be replaced because of damage or breakage (regardless of initial quality - at least in our case). The cheapest staff we purchased is still in use, as-is the middle and most expensive.
I have purchased a new one-piece wooden bo staff (on the light side) for my son who got bigger in the last year, handed down the best one to my youngest and gave the smallest bo staff to the school since we don't need it anymore.
I think one of the secrets (and it sounds bad but is true) is that hitting the end into the ground for fun is probably the reason people chime in to me saying they have damaged and broken staffs. I think that hitting the end on concrete or pavement cracks the wood inside to the extent that the staff is ruined. Our family was very aware of this and did not hit them into the ground.
Ok, thanks for all your comments:
Bryan chimed in that he would love a bo staff!
I received several messages with what sort of bo staff people would get next and it was overwhelmingly wood.
Annie chimed in saying:
"I asked one of my Senseis, and he said he didn't like two-piece bos because they would come unscrewed in the kotas very easily."