Ideally the property has positive cash flow (both units are recently rehabbed and therefore should get top of market rent) and you have extracted virtually all of your investment money.   

There is a lot we need to know before we can give you meaningful advice.

You will have little equity to extract from the sell. 

I had an especially bad day when I wrote the boat post -- but I'm faced with the reality of no career advancement, no meaningful ability to save or to lower my standard of living, a wife with a stalled career and two kids to raise, and RE investments being the only light at the end of a long, dark tunnel.

I could use that bid to extract costs for kitchen or bathrooms.

Hot Pads will give you a rent-ratio heat-map, which is going to similar to what you're talking about.Zillow has API's you can code against to extract data that you're interested and processes it yourself, if you're inclined to do-it-yourself.

More specifically I am trying to chain purchase rentals by extracting the equity from the previous one.

@Ron Rohrssen - when it comes to 5+ multifamily, I found that only a couple books were meaningfully helpful vs. the following options: coaching programspodcastsforumsnetworking deal underwriting / analysis That said, here are a few good reads that help lay the initial knowledge foundation multifamily investing:Crushing It in Apartments and Commercial Real Estate: How a Small Investor Can Make It BigInvesting in Duplexes, Triplexes, and Quads: The Fastest and Safest Way to Real Estate WealthWhat Every Real Estate Investor Needs to Know About Cash Flow...

Limitations of CAP rates include:they are only meaningful locally - i.e. comparing CAP rates in two different cities - or perhaps two distant neighbourhoods in the same city - is futile;they are only meaningful when comparing like assets - using CAP to compare a 11-unit apartment building and an 11-unit strip mall is dubious;they are meaningless when comparing residential (1-4 unit) properties - You see folks on BP all the time talking smack CAP rates on SFHs and quadraplexes.  

Net Worth is a paper tiger and is really meaningful only at two points in your lifebragging rights at a cocktail partydealing with your estate when it goes to your heirsLoad Rate, qualifications for loans, and cash-on-cash returns have no component of your net worth.