We're in the middle of justifying a similar project. Our potential systems are SAP and PeopleSoft for HR, Payroll, and Benefit administration. I'd say 2-3 times is a reasonable estimate for consulting services. Add more if you want to factor in the cost of internal labor. I've heard some SAP sources advise to allow up to 10 times the software cost for implementation.
Skepticism abounds around the costs.
If the estimates come out to much less than that, I'd be suspicious of what wasn't included. As much as we can at this point, we feel comfortable that the estimate would hold up without a lot of cost overruns during the course of the project. Of course, costs vary tremendously depending on what's being implemented, where, and by whom. Our experience would support the 3x estimate. Fleming College Well, Gary, we are amidst the very early stages of our Peoplesoft implementation, and we are estimating those costs at 2 - 3x the purchase price.