I remember going in to Model Railroad Equipment Corporation at 23 W. 45th Street in NYC when it was owned by Carmen Webster. They had a lot of Max Gray O scale brass equipment. The fellow who handled most O scale sales was Herman as I recall. I am not sure of his last name though. Possibly Lenzenweger? This was in the mid 1950's.
Max Gray equipment was never factory painted as far as I recall. Max also did some HO models marketed as Metric Models with the same blue boxes as the O scale equipment. I still have an HO NYC 19000 series caboose and two O scale express refrigerators with the boxes - one is REA and the other is a PRR R50b. I don't believe Max ever provided trucks for his cars.
The price marked on one of the O scale boxes is $7.85 from Model Railroad Equipment Corp.