How can you tell the value of a Toby Jug that is Royal Doulton?

Hi, If your Toby Mug is stamped on the bottom w/Japan/Made in Japan or any type of ink stamp and a few paper lables from Japan, it all depends on if its ink stamped in, red/black/blue, this would put the year made between 1930's to the late 1960's, this is when paper lables started showing up on the bottom instead of ink stamps. So most any mug w/ink, in mint to good condition would value out between; $30.00 to $65.00. And the paper lables, again in mint to good condition would value out between; $15.00 $30.00. Note: some mugs could even run at a higher value depending on the figural characters the mugs represent.