Is there any good resource with links to the relevant sites in particular states/counties?

Lower your offer price and move on.  

We built a single family home version of a 2 bed 1 bath with surface parking at cost with no profit all in with land for 175k in newark ohio, a suburb of columbus ohio. when we push that to 3 units and closer to the city for our build to rent model the numbers go way better. a 30k slab for a single family home is 30k, a 30k slab for a triplex is 10k a door. we designed a 2 bed 1 bath design at 668 sq ft and it's very good layout even I would live there, but I would never build anything that small again. there's no economies of scale. you need density and shared lines, resources, shared roof shared slab, shared windows, etc the cost goes way down.

I waited a few days and raised my offer to $255,000 and they accepted. 

Too risky for us.Regarding additional guest packages, you can easily change your tax situation by offering what the IRS calls "significant services".

I may specialize in VA loans, but I also offer a range a conventional, FHA, USDA and commercial lending options. 

For example, if I were to invest in Columbus, Ohio, could anyone share their insights on which neighborhoods or parts of the city offer good returns?

In what ways can you use the agent to be resourceful?

If the inspection reveals a bigger problem, either you can try to keep the deal alive by offering a seller credit, which could motivate the buyer to move forward, or the buyer walks away. 

I only have one that seemed to fail to launch.What I do get more is I offer to run a newbie through a transaction and/or show them the work in progress and I get either no show or barely show.