Detective Tools For A Fair Price

Trying to contact owners of vacant houses or other owner's whose letter was returned. I currently use the following ... 1) tax rolls on current property 2) tax rolls for owner in surrounding couties 2) public record documents in the surrounding counties 3) alternate addresses on other properties owned in surrounding counties 4) internet search 5) www.whitepages.com 6) www.netdetective.com What othe tools do people use. And specifically, who uses a skip tracing that is reliable, cost effective, and produces quick results? Thanks Brenda