Only two of these (Rowe and Seminick) were ever actually issued. The 1949 Lummis Peanut Butter cards are some of the most difficult of any type card. Sealtest is also very tough to find.
These proof cards are of varying sizes, so they could possibly have been produced to test which size would fit best with the various products. The inclusion of Pennock, who died in early 1948, tells me that these were likely produced in 1947 or very early 1948. The Pennock is his last known appearance on a card. All of these are unique, one of a kind cards (except obviously the Schultz where there are two of him).
Pennock $600
Seminick $300
Rowe $300
Walker $200
Leonard $200
Chapman $200
Schultz $200
Tom C