GBA's are only £60 now. i think thats bloody impressive myself. and cubes are similar too, £80 and a game. you know when Nintendo are about to release a new console its like a tidal wave, the whole sea draws back in on itself and then BANG!
Vortex... I could turn this into a flame war but I'm going to assume you're just ignorant of some of the details surrounding the PSP and not just being a Nintendo fan-whore. I'm addressing your last sentence: "if PSP is anything like the psone, it will require an external battery pack, a screen, and be really expensive/hard to carry places." Lets break this down one by one.
External battery pack: Nope, granted the battery life is pretty short. 2 to 10 hours depending on the game/movie. Presumably, the more the disc drive spins up, the shorter the battery life. Thus, a game heavy on FMV would eat up more battery life than a game that only loads occasionally then relies on what's stored in RAM.
A Screen: Well, last time I checked, the PSP's screen was built in ala Gameboy.
Really Expensive: It's launching in Japan on December 12th for 19,800 Yen, which equates to roughly $185 US. That's only $35 more than the Nintendo DS for a system that is at least a half-generation more powerful (DS being marginally more powerful than the N64 and PSP lying somewhere between a Dreamcast and a PS2).
Hard to carry places: They're roughly the same size, and the PSP comes with a strap. Woot.