ABRA is a network of boxer rescues working toward a common goal. The concept of ABRA is to standardized policies and regulations so that we can 'monitor' our own. They may be fine and ethical, but there is no recourse if they are not. Unless a puppy comes with a complete set of health guarantees, from a reputable breeder with a life-time money back guarantee, the answer is yes. Though rescue dogs have no known history, a puppy from 2 dogs without temperament testing, health testing and an uneducated breeder is just at much at risk.
Rescue is a labor of love.
It is a hobby and a contribution of time and money to even be involved. Some rescue groups will ask for an adoption fee that covers nothing more than the costs that boxer has incurred. Other rescue groups have a set cost to adopt a boxer. It will normally be an 'average' cost to that group to intake a boxer to that program. Though on some, it may be high, that overage is used to cover the next one that needs extensive surgery or vet care to be healthy again.