You can't always charge whatever you want.

I paid to have that done and did not charge for it. 

This is a frequent question and I've read through a few of the past posts asking for contractor references.

@Joe P.Yes, a dealer can use the installment sale with unimproved residential lots, as long as he/she elects to have interest charged under IRC Sec 453(l)(3)."

I am a realtor in Albany, NY and work frequently with investors.

What do they charge? 

They will also charge you to have an inspection by a 3rd party to make sure the work is done.

It’s currently 75% occupied (6 units) and also after looking through the financials I observed one frequent tenant falling behind on rent often and another falling short twice over the last 12 months.

Get a good handyman, you’ll use them frequently.

It depends on the state laws because if you're in a state that the charging order is not the only remedy in a lawsuit then your other assets can be in jeopardy that's why some people have Nevada, Wyoming, and Ohio LLCs even though they don't live that state because those LLCs provide the most asset protection.