See http://www.gun-data.com/tour7.html this may help you.
310 revelation 20 gauge
100 or so
about a hundy in good shape
Made by High Standard, value $150-$200.
$50 - $120
45$
50-150 or so
It's worth about $50.
IF your Revelation is a bolt action 20 g shotgun, its is a Mossberg 385. Value is between $100-$125. Cross reference numbers do not always match up perfectly.
50-100 or so
110-200 dollars.
50-125 USD