At the end of the day something is only worth what someone else is willing to pay for it.
I own a Carl Zeller painting and I have an original pamphlet that came with the painting and here is what it said about the artist.
Carl Zeller was received in Colorado and received his formal training at The Denver Art Institute. His early tears as an artist were spent traveling throughout the United States. At the Chicago World's Fair, he won the title of The World's Fastest Artist. Hw was one of three artists selected to renovate the paintings fo Charles Russell in Montana which had been damaged by a severe earthquake. During the forties, he began performing in theatres with various screen actors on their personal appearance tours. He also demonstrated for the Armed Forces, hospitals, schools and the U.S.O. Mr. Zeller has had many one man shows and has received over one hundred awards. His paintings are in private collections throughout the United States, Canada and nine European countries.
At the time the pamphlet was printed it said he resided in La Mirada, CA and devoted his time to teaching, painting and demonstrating.
The address of the studio was:
Carl Zeller's Studio
15573 Ashgrove Drive
La Mirada, CA 90638
I hope this helps!