Why are side by side shotguns always so expensive? Aren't they just a normal shotgun? I have seen plain SxS go for a few grand and have no idea why. Please explain.

The only SXS I have was less than 500 when I bought it. SXS are not as popular as the other actions O/U, pump, semi-auto so there are fewer made and some manufactures only make higher grades for their SXS'

CZ sells some nice SXS shotguns these days, which are made by Huglu in Turkey.

There are a number of reasons. For the most part the SXS business is a high end business. You can make them cheaper BUT the profit margin is minimal.
But back to the reasons. Barrel regulation, meaning making both barrels shoot to the same point of aim is an art form and is done by hand. Tolerances are tight and final fittings are also done by hand. Not only do you have two barrels but if you have a sidelock you have essentially two separate trigger assemblies. Stock blanks are of the very highest grade. The weapons are of the very highest quality, designed to shoot tens of thousands of rounds and will outlive their owners and their owners after that. There are no stampings, plastic, or molding. There is also the pedigree factor which is significant. You'll pay a premium for a Purdey or a Holland and Holland. On the other hand a Spanish AyA is essentially a Purdey copy. While not cheap an AyA is significantly cheaper than a Purdey despite being a nearly identical copy.

Same reason that a Porche is much more expensive than a VW. Or cheap flashlights on the counter at the gas station vs SureFire. Walmart tools vs Craftsman vs Snap on. Steak vs hamburger. High end double barrels cost quite a bit of money to make right. Want a cheap one? The russian bakial line is cheap. And you get what you pay for usually. Rougher finish inside and out, etc.

Good quality oats cost money. Oats that have been through the horse can be had much cheaper.

I have any number of cheaper SBS along with several other shotguns..my buddy who loves SBS has a Parker, I saw him pay $5K
for used and $700 to get a gold engraved trigger guard...and he
had about 5 or 6 Model 21 Win..in everything from 12's to 20's..
and I've seen him pay over $2,000 for a wood blank for stocks on
one of them..It's like everything else..you mostly get what you pay for ...and I think some gunsmiths have even made SBS rifles on Mod 21 actions..they were quite hard to make and very expensive, them and a few other things about bankrupted Winchester..DD

I have a decent CZ side/side and it wasn't all that nuch. Sure I am not getting a $3000 shotgun but it looks and works well.

I think its more of an issue of demand and availability...there seems to be more demand for semi autos, pumps, and O/U's in the US. People want these so they are available in various price points. I own 3 sxs's and shoot/hunt with them more than anything else...but when I show up at the range I get looks like I walked out of a time machine or something. Maybe there is less demand for sxs's because fewer people hunt upland game and small game (quail, rabbits etc)...side by sides are well suited for this.

If you look you will find sxs in the same price range as anything else...turkish made huglus run maybe 500-600, spanish made guns run from maybe 1500 for a decent field gun up to over 10k. Same with italian guns. The well known english guns command a premium...but that is a special category.

I've got two old winchester side by sides and I don't know what it is about them but every time I've dove hunted with one of them I have been a bird killing machine!! I love em!

M21 or M24?

X2

Yildiz makes some really nice ones as well

After a little health problem and opr..last yr or so, I got a 410
Yildiz SBS w/Briley type screw in chokes and have been well satisfied with it..It has selective triggers, nice finish, 28 in
bbls...and extractors..It was less than $500 out the door, has a
two yr warranty and Briley does the warranty work...and I've done
business with them over the yrs. and am well pleased...I plan on
making it my dove and quail gun this year..and I can carry more
bullets w/less wgt....Don