I base it more on number of bathrooms, square footage, attached vs detached, exterior material, type of roof, slab or raised foundation, size and make up of the yard/landscaping, etc.  

Not the labor but the deal finding and project management so that you learn more and can build on that foundation.       

With that as a foundation they recently asked me about doing a seller financing deal with them.  

If you are using conventional financing their will be capex items they will want to see in repair (roof, foundation, HVAC, etc) before they will lend.

List price was $72,500 and worked out a purchase price of $67,000 including $1,200 in closing costs covered by seller, foundation was repaired prior to closing ($3,500), and seller paid all of the realtor fees as well since it was FSBO.

Purchase price: $67,000 Cash invested: $16,600 List price was $72,500 and worked out a purchase price of $67,000 including $1,200 in closing costs covered by seller, foundation was repaired prior to closing ($3,500), and seller paid all of the realtor fees as well since it was FSBO.

I recently bought my house using the full 203k loan since the house had some possible structural repairs that needed to be done on the raised foundation. 

Build your real estate career on a solid foundation, not one built on dreams and gimmicks. 

We couldn't make minor repairs to the porch without permitting that would've necessitated installing foundation beneath it, $10-15k. 

They likely share a foundation, roof, exterior walls, fencing, hardscape, yard.