There's only three I can think of off hand for new guns.
Browning XT Combo (which I have and really like) a Beretta 682 Gold E (which a friend of mine has and really likes) and a SKB Combo (which another friend has and likes). I'm not too sure of the availability of the SKB anymore, you'd have to check on that.
I would recommend the Browning but the Browning and Beretta are real close in quality. The SKB maybe a little less quality and price but still a good gun for the money.
I second Jerry on this one. Buy a Perazzi if you can--it's money well spent. I know a lot of trapshooters have Brownings--I used to be one of them--but you'll be much better off with a Perazzi. There's just no comparison.
I've just purchased (this past Tuesday) the Browning Unsingle Combo from Guns Unlimited... so far I like the way it feels and handles.. Use the extra budget for getting the gun custom fitted to you... or spend the rest on shells..
If you decide to go Browning..get the Monte Carlo stocked gun and have somebody reputable like Ruck or Tron to name a couple to install their aftermarket adjustable comb..you'll thank yourself in the end as the hardware they will use will hold its adjustments forever and last just as long
Caesar Guerini!!! Great guns, state of the art features, very good triggers, great barrels, reliable, GREAT service (if you ever need it) lifetime warranty! A great value IMHO. I shoot CG, Ljutic & Blaser and feel that in this price range, <$4500, a "nearly-new" CG is a must-see option.
IMO Joel Etchen 687 Trap Combo for about $4100 new. They hold thier value well cause the JEs have special serial numbers and several unique JE features so those you buy them hold on to them. Moderatley used JE combo go for 3200 to 3800 based on condition and mileage.
While not new, the other contender would be a slightly used Guerini Summit Unsignle combo 34/32 that go for about $4400 to $4800. New ones are a lot more but every once in a while a combo pops up here. The new one combo exceed your threshold.
The Beretta 682 combos cost almost the same as the Joel Etchens and they are almost the same but their resale value is $2800 to $3500 based on condition and mileage. They do have a removable/adjustable trigger which the JEs dont have...
The SKBs are good intro combos and great values but not on par with the JE 687, Beretta 682 nor Guerini Summit combo. If you get them at the right price, you can resaell them for what you pay.