The concept of a free standing ER such as these in Texas is an interesting one. The overhead costs of starting one of these practices is pretty high though, including the cost of a new CT scanner which can run from about 1.5 - 2 million dollars depending on the bells and whistles attached.
If you don't care about new though, you can grab this steal of a scanner for $17,000 on Ebay. Hurry though. Only 6 days left on the auction!
Source
CT-scan-info.com. "How much does a CT scan cost?" http://www.ct-scan-info.com/ct-scan-cost.html
MedGadget. "Brilliance 64 Slice Scanner by Phillips." http://medgadget.com/archives/2005/04/brilliance_64sl.html