The Dell Axim is a great PPC. The higher models can even emulate Playstation games. The only thing I'm concerned with though is the battery. I've heard it's pretty bad.
As for Palm, personally I think the best choice is the Tapwave Zodiac. The 32 meg ram model is in your price range, and it's not only the best Palm, but it's probably the best PDA for games. It has an analog joystick, shoulder buttons, and 4 buttons on the right side. Basically think ofa SNES controller made into a pda, with an analog joystick. And with a 3d accelerator, it can do visuals that no other Palm can do. The graphics are equal with the Playstation, if not a bit superior. However it's also a top-notch PDA. And the battery life is fantastic. It also had a wide landscape screen, perfect for watching letterbox movies. The CPU speed isn't fast enough to run playstation ganmes though.
The other Palm is the Tunsten III, which is another good choice. However, the screen is smaller than I'd like, and I heard the battery life isn't as good. It is a bit faster than the Zodiac though, and within the same price range. Really though you're not going to find many programs that need the CPU speed the the Tungsten III can dish out, at least until they make a Playstation emulator for the Palm