For accessories for windows mobile phone, try
www.pdair.com. This is Hongkong based site. They carry many accessories for these devices and the good thing is they provide free international shipping. I ordered a leather case, sync cable, screen protector from them and they all are in good quality.
There is one more site
PDA Accessories, PDA Accessory, Accessories for PDA, Pocket PC Accessories, Pocket PC Accessory, Handheld Accessories, Handheld Accessory, Handheld PC Accessories, Handheld PC Accessory which is also based in Hongkong. They don't offer free shipping but when i ordered an extra large battery for my Jasjar, they charged only $7 for shipping.