The other end of the spectrum
Generally when I read about Doubles they are high end guns and in most cases out of reach for many of the average working guys. Its taken me ten plus years of wanting one to be able to buy a real one. I tried over the years and had to satisfy my self with a double barrel muzzleloader and a shotgun with barrel inserts.
A few years ago the Bakail's hit the US market. At first they were just the O/U's that looked vaguely Valmet 412-ish and were 30-06, 308, and 223. There was lots of talk about SxS guns coming in 45-70 and 30-06. The Remington "take-over" of imports from EAA seemed to have ended the SxS's for awhile at least.
Now the 45-70 and 30-06 SxS's are available for well under $1000. The O/Us are usually under $500. To be clear they are crude, usually on par with the Bakail shotguns; but they have a certain charm, kinda like a T34 tank. In this case the price point has a quality all its own. They are owner "regulated" by a jack screw which moves one barrel into position to match the other.
I have just purchased a SxS 45-70 and 30-06. The beauty of these guns is that I wont be afraid to take them to the field when the weather is bad. I havent had a chance to get them to the range YET and play with "regulating" them. The 45-70 is limited to standard velocity ammo; but that should be fine for Deer, Boar, and Black Bear. They use a grooved rail for scope mounting (think a .22LR grooved receiver), which may be an issue finding rings or as easy as tapping for a Weaver mount.