By identifying the right buyer within our network and streamlining the transaction process, we added value without requiring extensive renovations.

A lot of buyers think that too. 

The old owner unfortunately locked his tenants into $800 leases which scared away some buyers before he listed.

basically if anyone has any tips when it comes to researching plots of land in order to make the right purchase i would greatly appreciate it get with a realtor. we underwrite land at no more than 10% of after built value. in our market we build under the average new build value which is about 515k. we like to be around 420-450k and smaller footprint about 1500 sq ft with attached garages. we build close to urban core where everyone wants to live and net migrations match up. but suburban is fine. if you give more context I can help but in most markets land is a buyers market. most people aren't looking at it or buying it. 

But as Chris mentioned, buyer has to own the property, not a contract for deed or something like that.

Is just the fact that no garage could be a no go for some buyers enough to build it even if it only raises the value by the actual cost?

If not, who do you believe the natural buyer is and why do you believe they will pay retail when they can replicate what you accomplished with any number of available properties on the market at any given time?

When I drive for dollars, I just take notes of the addresses in my phone and add them to my propstream lists later.As for cash buyers, I don't think there's such thing as too many buyers on your buyers list, although you do only need one to close a deal.

I saw once where a developer gave the buyer a pass on paying HOA fees till a house was built on a lot. 

The seller's LLC pays capital gains tax and depreciation recapture, while the buyer's LLC uses the purchase price as the new cost basis.