It is really not to difficult to find a shorter barrel, fixed choke, O/U of quality within the $500-$600 range.You just need an idea of what to look for and go about finding the gun you want, with patience. In general the two top clays guns today, in the reasonable price range, are the Citori and the Beretta with long barrels and most times one fits a shooter and the other will not, just depends on the shooter. The 101s you will see at the skeet range. With modern shells and hunting upland birds an IC choke is about all you need so a good combo would be IC and Mod in a fixed choke gun but mod and full is not a good choice. I sold a Citori last year, in the box, as described (fixed, IC & Mod) with 26 inch barrels for $600 but the gun was as new and I had bought the gun for $500 the year before as a project gun for a new set of barrels, just did not get to it, before I found a nice 30 inch gun. I sold the 26 inch gun to a bird hunter.
The cheap import O/U guns for the most part are not of quality and the major problem is that the internal parts may not be heat treated properly, this is a major complaint. With an O/U the presence of soft sears, hammers and firing pins will lead to a myriad of problems.
Once you buy a real nice shotgun, you wonder why you did not do it for yourself a long time ago. But you have to get over the dollar hurtles first.
Ed