You'd be better off starting another thread Richard...
but I'll answer your question like this ....my buddy owns a used gunstore ( has about 300 shotguns in inventory, 200 rifles, 500 handguns...) ...at all price ranges ...$ 300 - $ 3,000 ...and the last time a young guy came in with a Mossberg O/U trying to trade it in on something ( it was pretty new - hadn't been shot much ) ...he told the guy he couldn't sell them at any price...and didn't want to insult him and just offer him $ 25 for it ...
They don't hold their value, metal workmanship is suspect, barrels may not shoot to the same point of impact....the few I've seen, get very loose in the action ...so I suspect the barrel to receiver connection is not well machined or is not very strong.
If you want a low cost O/U ...at least look at a gun like TriStar where they have a 5 yr warranty ( Cabelas and others sell them ) ....or maybe a good used gun ...like an SKB ....or even a Browning Citori ( but there are 28 models of the citori - so you need to know what you're looking at -especially in older models ), or a Beretta. Beretta and Browning have long given you a lot of gun for your money..../ you have to ask yourself why a Citori Lightning that sold new in 1988 for $ 750 ...with even 250,000 shells thru it today(24 yrs later), is still worth $ 1,000 - $ 1,250 on the used market ( its because its a solid gun / well made / not fancy - just well made ). And you have to wonder ...how can Mossberg sell that gun new for under $500...or whatever it is today ...