Embedded System Hard Drive

I have many devices operating on many different operating systems. Some are proprietary, some are unix, linux and windows. Some hard drives are SCSI and some IDE. I am looking for a program that would allow me to clone the hard drives. Most manufacturers will sell a new hard drive with the software preinstalled but the cost is prohibitive. I need a method to keep hardrive’s on the shelf ready to go should one fail. I would like to build a dedicated machine to do this. Is there appropriate software out there or am I going to have to buy a cloning machine?