One was listed on Gunbroker in 2009 with minimum bid of $400, quick sale of $510. It did not receive any bids at that price, though that seems a reasonable price if the quality is decent. El Dorado seems to have been a small, private maker doing customized Rugers.
100-600 or so
100-300 or so
25-100 USD
50-150 usd
100-1000 depending on specifics
500 USD
40-190 usd
15-75 usd
50-300 usd
50-260
50-500 USD depending on specifics
100-300 USD