Numrich Gun Parts is the default. You can often find cheaper parts at other vendors. Search online with the model and "parts" and you should find several sources.
You will probably have to have them made.
Modle 101 1380 410 shotgun
Gunpartscorp.com has about the best selection of gun parts in the country. Start there.
You can try e-gunparts.com or have a machinist/gun smith make them.
Try e-gunparts.com
You can get parts and information at the following web site: e-Gunparts.com/Forums/MessageBoards. The Revelation 310C is the same as the Mossberg 500C.
310 revelation 20 gauge
And your question is?
Yes.
$50-$100
Savage
It seems most Revelation Shotguns were made by Steven/Savage company.