Penny error hunting

how many here regularly search for mint error on cents? I have often wanted to, but was unable to see the errors. I have tried several loupes, but never been able to get the knack of using them. My wife got me a new one for my birthday. I can actually use it and see what I am looking at.
Is there a market for error coins? For example, a 1999 wide AM lists redbook for $500. What is the reality. Does anyone have a percentage? Example one mint error per 10K searched or what.
Thanks
Is there a market for error coins? For example, a 1999 wide AM lists redbook for $500. What is the reality. Does anyone have a percentage? Example one mint error per 10K searched or what.
Thanks