Cost Segregation - Scale?

[Tom Sproul]

At what scale does it make sense to start exploring a cost segregation study?  Does the cost of the study scale with the size of the investment?  Who does these (not looking for specific companies), is it accountants, lawyers, agents, and/or contractors?  Seems like an interesting niche...

I had always assumed these were for larger scale commercial investments, but in the recent On The Market episode, Brandon Hall used an example of a $100k property.  Not sure if that was for easy numbers or if this is something that can apply to most six-figure investments.  In my head it's always been a 7+ figure investment tool... 

Thanks in advance!