Brother I am not a fan of aluminum receivers. I have been shotgunning all my life like a lot of folks on this forum, but I have been shooting sporting clays since the early 90's . From the inception. If That's the price point you are trying to stay in, I would recommend looking for something used. Browning, Beretta , some one mentioned the little Ruger Red Label, if you can find one. All steel good long standing record of reliability. the older made in Japan SKB's are excellent as well. I personally would not spend less than $2k on a new o/u. And it would have to have at least 28 " barrels. Also the triggers are probably gonna be a little better as well.
If you want something really lite and don't mind chasing empty hulls, there are a couple of real nice autos that fit the bill as well.
Hope this helps!
J