Cost comparison of using Oracle on os/39

The company that I am currently working for are moving from IMS databases to an Oracle system. I just read a realy good article in SD(Software Developers) magazine that argues for the case of useing the Main Frame. This was the August issue that Iseen this. Anybody know where I can get a cost comparison? Im just a grunt, but currently I think we will waste money going to a Sun or R6000 platform. Also, from what I have read. The operation costs are much lower when useing the main frame. Any input is much appriceated. Dan