There were actually several different versions of the
RFU made. Obsession 2 and Expression 2 models are compatible minus the labels being different. Obsession 1 and Expression 1 model RFUs are not compatible with newer consoles.
I just did a cursory search of the
stage lighting section on eBay and didn't find an
RFU that was available by itself. If you care to share the link I can see which model it is and confirm whether it is a RFU1 or RFU2.