I've bought a couple of small mobile cases from Auto Zone that I thought were perfect for my x10 minipro. They have a front pocket for the phone with a velcro flap to hold it in and a small zipper pocket behind which I carry the headset and a spare battery. It's a perfect fit for the phone.
The only problem I have with the case is that it is very cheaply made and eventually the swivel for the belt clip wears out (which is why I've bought a couple of them). I'd love to find a similar case (but better built), but I haven't had any luck finding one.
I posted here because I ordered the new minipro last weekend, hopefully it will be here tomorrow or Friday.