It is difficult to answer this question because SAP is not like buying a car or a finished product. It's more like building a house - the raw material is only part of the overall cost. Furthermore the final cost depends on how large of an implementation is desired.
As you might expect, the largest cost involved in a SAP implementation are the people doing the implementation (e.g., "construction"). It is unlikely that you could buy SAP software without also purchasing some SAP consulting time.
Few SAP implementations cost less than a million dollars and many have ended up cost ten million or more.