Dave, I checked the MLS (all reports done, nothing else to do). 1 VL sale in Round Lake in past 6 mos, 18 in last 12 mos, 49 currently listed. I agree there is a strong case for functional obsoloescence due to market conditions. Obvious over supply. Check Lake County Assessor site. There have been a few recent developer closeout/auctions of un built home sites in Grayslake and Mundelein, all located within subdivisions. Both were handled by Inland. It'll take some time, but if you search by partial PIN or street name you should find at least one or two. Even if you have to adjust site value for location (that little area labeled "Support for the opinion of site value), you will at least have a defensible position. I strongly advise against the $1 site value. Tried that in Englewood a few years back and it was a nightmare. Find one good land comp and reconcile your value with emphasis on the sales comparison.
PS No Income Approach? 20 4+ bedroom 2 stories currently listed for rent in RL/RLB just kidding.