Have your closing docs out and know what ratio the county assessor applies to land value (ie 300k assessed value, $50k land =1/6). 

Seems to me my options are...SELL - If I were to put it on the market I think I could reasonably get $2.8M - $3M, but at a 2.9M sale price my return on my initial investment is only 38%, or 7.6% a year over the 5 years.

However, you have to be extremely careful financing 100% of the transaction as you still need reserves, closing costs, etc. and make sure it cash flows.You didn't mention if this would be a rental or owner occupied. 

In addition to your down payment, plan for closing costs (around 2-5% of the purchase price) and set aside at least 3-6 months of expenses for repairs, maintenance, and vacancies.

What are the costs for the value adds, the expected hold time, and the expected sale price? 

For a quick analysis, I get as close to the 1% price to rent ratio rule for cash flow in Indiana when I was doing my search and narrowing down properties.

Otherwise they just run around and bid projects for people that don't close.

Has anyone saved money and closed with one of these new upstarts?

A client can close on a new property with us in less than 45 days so no long closing or pre construction risk anymore with our program.

You can find the most recent sales price for the property on the local tax records website or by doing a quick search on Zillow.