Second the AA S200. They are closer to 600-650, but well built and worth every penny. They have been made quite a while, but you rarely see used ones for sale. Owners won't turn them loose.
Marauders are also still a good value, and if you're patient they can be scored on sales for ~360. There are a million parts and mods for the Marauder. But if the only thing you do is spend $50 for an "MDS" lightweight hammer, it will almost double the rifle's shot count with no other changes except a little retuning. The Mrod isn't flashy, but it is super easy to tune and probably has the best trigger of any airgun under #500. If somebody wants to argue best, at least quite nice.
I"m also a big fan of the BSA Scorpion SE, which you might find at that price point if you find a decent sale. Pyramid Air has a birthday sale every year about the third week of May with good discounts. That is when I bought my Scorpion SE a few years ago.