I found a set for my Enders Special Service a.k.a. crescent on eBay of all places. It took some time and alot of questions, pictures and measurements but was worth the wait. There are many barrel sets that will fit with a little tinkering.
I was offered $500.00 for mine.
50-1000 or more depending on specifics
Blue Book of Gun Values
Single shots, $50-$75. Double barrel, $150-$250.
HAVE IT CHECKED OVER BY A GUNSMITH FIRST!!!!!!!!!!!! It is an old shotgun.