Sporadic master brake abs booster unit failure

[Starman52]

This problem has my wife freaking, Out of the blue she has no brakes or very little. Never know when it's going to happen. I don't drive the thing enough to have it happen to me. Replacement units look a little pricey. Are these things prone to fail? It's an '06 sport v6

 

[earthrealm]

there are countless threads on this issue.
replacing the unit is the route taken by many, you can get new or used units as low as $400

 

[AuSeeker]

there are countless threads on this issue.
replacing the unit is the route taken by many, you can get new or used units as low as $400

Used master cylinder for $400 very possible, but a new one for $400...WHERE???