The Repros aren't being made anymore, and have assumed some collector's status. Their asking prices make that SKB look like a bargain.
There's plenty of classic doubles out there,LC Smith,Ithaca, Parker, and my personal favorite, Fox, all made great guns.Unfortunately, everyone knows it now and prices are horrendous.
Buying a SXS is a path full of traps and pitfalls. Just because it's a double doesn't mean it's good. Lots of junk was either made here or imported, and lots of stuff that was not all that good or safe new is now close to a century old.
Still occasionally one can run acoss a decent deal on a Continental or English boxlock. I've seen French guns of definite quality go for less than $1000, and some for less than $500. One I owned for a while handled like a best gun and came in at 6 lbs, 5 oz. IIRC, it was sold to me for $300, and I made some profit when I sold it.
Skip the Belgian stuff, most of it here is junk. People wanting good shotguns in the 19th Century went for the classic US makers or a Brit gun.
HTH...