The PSP Go is available for pre-order for $249.99 at Amazon. 

Amazon will not charge you until it ships later this year.

Check it out:  Amazon - PSP Go

Product Description
Introducing the smallest and mightiest PSP system yet. Download rich, immersive digital gaming or the best movies and TV shows saved directly to the ample 16GB hard drive. Browse the incredibly deep lineup of PSP gaming and movie content on PlayStation Network. Show off content via the ultra-crisp 3.8 inch LCD screen on the most portable PSP system yet.