The famous "Beatles painting" from their '66 Japan tour is going up for sale. It sold for $155K in 2012. I think the $400K - $600K estimate might be too low...
https://www.cnn.com/style/beatles-japan-painting-1966-auction-cec/index.html
https://www.cnn.com/style/beatles-japan-painting-1966-auction-cec/index.html