They also charged just under 250 for landscaping, even though there is no grass to be cut. 

I think it is quite possible that it would dehumidify a larger area but for the walls, but ofcourse who knows for sure.I have no idea on the install price because we got the house when an aunt died and she had it done way back right after hurricane Irene flooded the whole basement, but there wasn't a choice on pro install because a hole had to be cut into the foundation as there was no window, I have a feeling if a venting spot existed it would be a pretty easy diy project.

I have no experience in residential.... would you consider this a waste of time or something worth doing (my cut would be only 4,000)

The new Tax Cuts and Jobs Act is very building owner friendly and there are big tax savings opportunities available. 

For me, it's usually around $12-15 per SF for a mid range cosmetic rehab, but usually that can be cut some here and there like painting wood paneling in a room instead of tearing it out, texturing, then painting, just as an example. 

There isn't a short cut to a right answer, many things will work, if you do the work. find your local real estate investment group and start listening to their business models.

I cut it with tin snips and a knife. 

I'm planning to do a house hack once I cut down some of my debt and get more reserves.

I would also compare those two quotes to check for any coverages that you can cut on or that seem out of norm from the others.

Our family's goals are to pay off our consumer/student loan debts and have enough cash flow that I can cut back my hours (maybe to 0 hours) and travel full time in our travel trailer for a few years and then maybe go back to work but probably not.