In the clay target world....semi-autos around $ 1,000 - $ 1,500 are very popular....and by far the most common are Beretta gas guns. If you shoot about 400 shells a week -- that works out to about 20,000 shells a year, and I've seen some very good shooters buy new Beretta 390's or 391's...and they'll last about 3 yrs or 60,000 shells. They sell them after the 3rd season ...buy another 391 and do it again....
The 11-87 is older technology ...but its still a good 50,000 shell gun / if you keep it clean and properly lubed ( thoroughly clean it - trigger group out, etc ) after every range trip ...and inspect it for worn parts...it'll serve you well.
----------
The better over unders ( Browning and Beretta ) are going to give you the most gun for your money - but new, these guns are $ 2,500 - $ 4,000....not high end guns / just good serviceable guns that will go 500,000 shells ( not 50,000 like a gas gun )....and you have 2 barrels, for 2 different chokes.....better swing characteristics, etc.../ and reliable ( if you can stuff a shell into the chamber - with cracks in it, etc ) - and can lock the gun closed, it will probably fire --- and no, you can't do that with a semi-auto...
Over Unders ....and there are lots of them out there under $ 1,500....will probably not hold up to big time target use ( but 500 shells a year is not big time use )....so you might find an old SKB, maybe an old Ruger, or even an older field grade Browning or Beretta --- that if they "Fit" you --- will last a lifetime.....but stay away from a lot of the cheap Over Unders....
------
50% with a short barreled gun and a fixed choke is very good....so you have an eye for it and some talent....now its about consistency / killing the targets you should kill, and working on the ones that cause you some trouble../ not going 3 for 8 on one station, 6 of 8 on next, 0 for 8 on next.... a goal of 6 out of 8 on a station is 75% ....and that will get you into the low 70's out of a 100 in a shoot...
------
You can shoot all of these games with any gun you want....a pump, semi-auto, over under, even a side by side if you want...and any of them will work in the field as well. Lots of guys shoot 4 or 5 rounds of sporting clays a year ( 400 or 500 targets ) just to tune up for bird season...with pump guns, semi-autos, etc...so you don't have to spend a lot of money to play the game.
To get serious about sporting clays...and shoot registered targets...its about score / and good equipment to get competitive. But there is nothing wrong with just going out 4 or 5 times a year for fun too.
--------
and have some Fun !
But remember the cost of the gun...is not the issue ! Targets in my area are about $ 40 per 100 ...and 5 boxes of shells ( $35 ) ...to shoot that 100 bird event...makes it about $ 75 for the day....and if you do that ...twice a month, $ 150 a month ...is $ 1,800 a year...!!
Shoot some Skeet and some Trap too...to keep your practice costs down / and work on the fundamentals of stance, gun mount, swing and follow thru.../ especially Skeet will help your sporting scores big time!!