The installation of the boxes will run around $30 a door versus around $500 a door to run the vent outside.  

What do you guys recommend as a referral fee on a wholesale deal?

Selling on the MLS would cost $13.2k in realtor fees (at 6%) putting you at 206.8k from $220k, so there's really nothing there.  

I know that I could close this deal using a double closing with a transactional funding lender but of course I'd like to minimize my fees.

You just need to run this through a filter and see if it makes sense to control an asset with zero bank involvement up front...and assess what structure of the deal takes on.I just offered on a 6-unit last night...and usually keep consistent opening terms for debt-free properties: 10% down, pay sellers closing costs and all document prep fees, pay realtor commissions, at or near list price (if it makes sense), 4-5 yr balloon, 30-yr amortization, 6-7% interest.  

Also why not a SFR that does not have HOA or fees.  

-Does their memory of his fees and process match up with what he has told you?

The test was $85 and the license fee is prorated by where your birthday falls.

Installation is not difficult VERY similar to painting. 

Understand the fees involved and calculate the total cost for an entire year of management so you can compare the different managers.