I'd suggest pulling sales and under contract data from your MLS - just for vacant land. If there are similar parcels that recently sold, that should help define the price. You may need to adjust for amenities - i.e., are there utilities on the property, are there any special features, etc. Your broker should be able to help you do this as every location is different.

Then use only raw land and many appraisers will use price per square foot. I usually use price per acre and adjust accordingly.

That would be a normal CMA which you could do on your MLS or Cloud CMA the same you would for residential property, but you're just pulling vacant lots within the same lot sizes and or acreage as the subject lot, then you could also pull lots with improvements (houses) of similar size to get an idea of the developed value (obviously the house floorplan is a variable). 

Candice A. Donofrio and I are on the same page this morning. Good luck!

Yes, you just need to filter the comps to suite your need

Like kind property for like kind, especially if house is a tear down. The lot is improved though, you have the utilities there.

You have some good comments here that guide you through what to do. 

I will add that you will want to keep in mind the location of the lots and how they vary based upon the data you extract from the MLS.

Yes

In my MLS we would have to do a land search only & then you won't end up with any comps. We are already a built up area. Have only had these situations where the house has burned down.

The lot size is only of of the factors that should be considered in a CMA. 

Using lot size doesn't always work here. Sometimes a 1/2 acre lot will sell for the same as a 3 acre lot, or a 3 acre lot will sell for more than a 10 acre lot. I'd just check land comps for the last year and use a range for lot sizes. Or if you have the assessed land value, let's say it's $100,000.00, search land sales in the $50 - $200,000.00 range, then check lot sizes.

I know you can make manual adjustments that may not have the right headings but do allow for plus or minus values. Remember, all formulas lead to a conclusion in their moment and for their purpose. That's what we are after. NOTE: Real Estate is alive and always on the move

Try your MLS technical help or consult a licensed appraiser as to how they approach the issue. 

Get the baseline from the tax appraisers' website for the land or unimproved portion. Adjust with most recent sales data for closest and vacant land.
Tweak that value based on options currently available for buyer. Religious number crunching will give you a feel for the 'crazy factor' that may also color the target SOLD price.
Stand by your numbers. Builders know their costs and the margins they need and they are NOT the same between builders. A builder who intends to do a 5x infill has different parameters than the replacement builder.

I would just do land comps