They charge what plumbers charge for labor and material to replace plumbing.

https://abnb.me/ug2awNfYPEbHad to reinvest most of the profit to add amenities, fix pool, add replace the equipment.Looking to add more amenities like wooden canopy with hanging chairs and fire pit, sauna, tiki bar.

renovation including a roof replacement Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

You'd have to engage a grading contractor who might be able to give you a ballpark estimate, but it would maybe have to be engineered with rough and precise grading plans to determine costs. 

My main goal is to identify an opportunity that can be scaled from a couple of spots to a dozen, to several dozen eventually without the need to completely re-design or re-engineer the layout without respect to providing utilities. 

land has very little value if existing homes are selling for less than New build replacement costs. which is pretty much half of the US.. and especially in the mid west and rust belt areas.. building lots have value in dense urban areas where new infill is going on in a big way..

I am replacing a carpet on a unit.  

A lot of these properties I'm looking at, are mainly just outdated ( Fixtures, cabinets , older appliances ), needs carpet replaced, most have wall paper on the walls , needs an updated paint job both inside in out .So not really things that make it un-liveable , but just mainly need updated Which brings me to ......

The seller has agreed to let us out of the contract but does not agree that we should receive our earnest money back because he says he is able to bet everything damaged and stolen repaired and replaced before closing.   

Are there a ton of renovated properties or are they mostly selling far below replacement cost?