Both the Park City MLS and Wasatch Front MLS, which I have access to both, will have that data. Usually the data stored will be for the past 12 months. This is the same data an appraiser will be looking at when a person is purchasing your home and getting their loan. I'd be glad to offer any help you need in looking for comps.
Nancy Watkins, Broker
ABR, CLHMS, GRI, MS, SFR
Utah Homes & Land, Inc
801 824 0222
Comparative sales data isn't something that is published as part of the public record. Local Realtors do have access to most of the data.
Let me know if I can be of assistance.