Cost to install power brake booster

Cost me ~$25 net. I got a booster off a 74 Dart at PickNPull, used just the firewall brackets w/ a booster/MC from a 95-99 Breeze. You can see in my avatar at the left.

I cleaned up the booster and sold to a guy here for $15. I got a new Breeze MC (for backup) for $20 on ebay. You could pay much more.

You can also mount a modern alum MC to a Dart booster, using a 2-4 adapter plate ($30 ebay). I did so on my 65 Newport because I already had a new booster/MC from rockauto ($70 clearance, grabbed that baby quick).