You clearly don't know our market in Sarasota.  

I am exploring the possibility of purchasing an off market plot of land, building a modular home, and then selling it.

I'm curious what more experienced investors will leave to finish repairing after they list the property, but before they start to show it (or lease it).I start the marketing about two weeks prior to completion, with an advertised availability date of one week after completion.

Charge market rate.

As for the target market, we are focusing on Brownstone buildings in New York City.

Therefore, working with a single real estate agent doesn't make much sense as it will limit you to his/her very limited inventory and he/she might have as main objective to sell a property to you take advantage of your lack of knowledge of the market.

The PNW is a great market with tons of opportunities!

Our strategy has always been BRRRR, and we live in a historically cash-flow** market. 

Really the person that is going into the flipping game should know the market very well to do these comps on their own, and back it up by asking their trusted real estate agent/professional for confirmation.

Low or no down, seller financing and low or no interest with a balloon payment later is the holy grail (location, building condition, market also matter but it sounds like you have all that).