A ball park $ figure for limbing?

I'm looking at a potential investment property that needs alot of work. This big old oak?!? Is over handing the roof pretty badly and effecting the roof. I'm trying to budget for an offer on buying the place but I have not idea how much this would cost. I'm guessing multiple thousands but no guess on how many. I would want to limb the over hang and probably the other side too rather than cut the thing down. Could anyone ball park this for me please. East coast of Canada