What are they worth in really good condition?

I'm assuming your talking about a pump action? I picked up a "beater" for $100. I like it, even shoot skeet with it on occasion. I don't know what you mean by "really good condition", but Mossbergs are inexpensive brand new.
Personally I wouldn't pay more than $150 for one unless maybe there is something special about it. Just my .02, I may be wrong.

Really good meaning like new ....they want 350. Most gun shows the 410 s seem to be a hot item....probably for the reason I am looking....would be for my grandson but I would probably prefer a nicer model so he could hand it down himself so day...

you can buy at Walmart for under 300 new

That's why I asked....thanks
Big flea market..I'll bet the guy bought it new just to find a sucker.....

Assuming this is for the Model 500 pump and not one of the many bolt action guns, $200-$250 if brand new condition with box, no more than $220 if missing box. If less than perfect, then up to $200 depending on exact condition.

I am not a Mossberg fan and would be more in line with the other poster on prices. I would pay trade in value for one but not used retail and certainly not new in box price. But I have a few 410s already so have no pressing desire to have another one unless the price was too good to pass up.

I've picked up two Remington 870 Express shotguns in 410 for $200 each off the used racks of a local sporting goods store in the past year. Both were hardly used and were typical for other shotguns at the store. I kept the one for the wife to use on pests in the garden while the other went to my niece's son as a beginner gun for squirrels.

If one of the many bolt actions one sees around, then $125 would be the tops I would pay for one.

PM sent

410's are "hot" I guess. I shoot alot of shotguns. 410 side by sides are "hot", any old Sears or Stevens side by side for instance, I see guys asking $1000 for....asking don't know what someone willing to pay for them.
I bought a new Rem 1100 Sporting 410 that is a hoot to shoot and paid $850 for that. Older Rem Wingmasters in 410 & 28ga are "hot".
Mossbergs just don't have that much value. Not to knock them, I have an old 410 pump stated above, its built like a tank, and never fails to function, they just don't bring high prices.

$350 is above impulse-buy price, I sold a nice one w/synthetic stock for $300 in the last few years
(If I could find a Rem Express in GC in .410 for $200 I would be all over it like stripes on a skunk)

Spilogale putorius called, looking for you...

sorry, didn't mean to raise a stink

You didn't "spot" the weaker joke?

yeah, but I had to google first.