Picked up a rebranded Mitac Mio 168 for £200 recently; Not the most powerful machine and no BT/wifi, but it comes with Windows Mobile 2003 and has a built-in GPS reciever, handy for in the car or when using PocketFMS. Supports SDIO via the SD/MMC slot and I picked up a sandisk SDIO wifi-card for £27 quid.
For sheer power and screen clarity however, as well as lots of connectivity, you really can't beat the Axim mentioned above.