@Gray KarnesHaving a private lender who funds 100% of purchase and rehab and wants to be a 50/50 partner is pretty typical.  

I'm thinking a gray carpet to better mask the dirt and stains. 

it's stone or brick...are we spraying it with Thompsons water seal? 

Paint the walls; can't go wrong with some light gray in 2019 (like Sherwin Williams Agreeable Gray).

Quite frankly, I'm not a fan because because it gives the appearance of everything looking grungy and dark as some here have pointed out, especially if the decor is too homogeneous; that could be why the ceilings appear gray? 

Otherwise you'd need a sewage pump.If you're shop didn't have a bathroom, just gray water, you could do a gravel pit.

Everyone on here brings up good points, but there are always reasons why something is a little gray.

You will need to research the laws of your state and navigate through the many gray areas.The fact that the property will be owner occupied could throw a wrench in your deal vs. a non owner-occupied property.

This is kind of a gray area because the alarm is also used at houses that I own in my own name when they're vacant.

I use Sherwin Williams Agreeable Gray with white trim.