Depends on when he got it. If he got it when they were new, it was expensive at the time, but affordable and a steal in today's market. If he got it later, especially after Mathews, Williams & Mantle died, then it was probably very pricey!
I got the litho in a grayflannel acution in 2006. It is signed by all of the members and the artist, Ron Lewis. And yes, it was pricey In addition to this one I have the 3000 hit club, Negro League All-Stars and King of Kings (Ryan, Aaron, Rose & Henderson) lithos by Lewis and a 3000K club autographed poster as well.