The Planning Department has a cost analysis program for developments which should provide breakdown of government cost numbers per family - at least per household. A minimal rough estimate was a $1000 increase in tax expenditures for every home built.
County portion of school costs are about $4,000 per student. The county budget will also provide the overall costs of government provide services, but it's difficult to allocate the costs by a per capita basis of increase in population. More people does not necessarily mean increase in use cost, in fact sometimes it may decrease per capita. - but you already knew that.
Admittedly I have not read the Wikstrom report, but according to Lisa Parkin's letter (very Pro BigBox) in the Wave today, we have a tax leakage on $29 million per year in sales. That amounts to an expenditure of about $6000 per year for every family in the county or $500 per month. Do you spend $500 per month on "groceries and general merchandise" outside of Wasatch? If so, would you stop because WalMart comes to town? Those figures, IMO, are grossly exaggerated. What is the actual sales projection for a Wasatch big box? How are those "tax benefits" computed. Personally, I'd be surprised if my family spent $20 last YEAR and I sincerely doubt that, WalMart was here that we'd spend $200 per year for some item of convenience that I could not get elsewhere. This is the same faulty logic used in the Airport economic analysis.
It is important to note that the sales tax goes mainly to Heber - not the county, Parkin quotes $77K to school (which would be offset by increased people moving in) and $89K to Wasatch.