Vegas' Alec Martinez could be a great addition at a low cost for a consistent veteran who has won multiple Stanley Cups. He might be older now but if they can get him at a low cap hit, it may be worth it.
As far as stay at home D go, TJ Brodie would be good for the Bruins as they could land him at a cheap price since he struggled last season but has proven he can be a reliable defenseman in this league.