usual_suspect,
From my experience, ordering a case and having a company remove the PS is not very cost effective. It is better to order a case that doesn't come with a power supply or to order a case with the power supply and sell the PS later.
For example, the 600 Series Antec cases come in 3 varieties:
600 - NO PS
630 - 300W PS
635 - 350W (maybe 330W) PS
It is far more cost effective to buy the 600 or to buy the 630 and sell the PS, then it is to buy the 630 and have the company remove the PS. If this is an option for what you want to buy, then I recommend using it.
BTW - I second
EMSComputing. I also like
Directron