At $650, the Beretta 3901 or the replacement, the A300 Outlander, will give you a decent semi that will do the job and not break the bank. Pumps are a distinct hindrance on targets that involve pairs - which 95% of sporting clay targets do. It is not as highly refined as their other gas guns that cost closer to $2000, but the mechanism is very close and about as reliable as you can get.
Next time you go sporting clays shooting, especially at a tournament or charity/fun shoot, take a look at the gas guns - they will typically be ALL Berettas. While the O/U rules the roost in sporting clays, about 25% of the shooters use semis. Of that, 98%+ use a Beretta gas gun, including several of the national champs. They use them because they work and are reliable - period
The A300 or 3901 is typically found at wally world, Cabela's, and similar stores