The easiest way to start to get a feeling for the value is to look at multiple comps in close proximity to each other and analyze the differences in the properties and the different in rent. 

I'd like to hear about opportunities in the eastern half of the state.

I would consider myself a jack of all trades when it comes to construction (and master of nothing as the second half of the saying goes).

This is simply because it seems to be the easiest way to get into real estate with the least liability. 

Much less likely but still possible would be a recommissioning of the rail line for an industrial use, in which case I would think the value of this property would plummet.The seller has dropped the price several times down to around $150k, having bought it for $170k in 2007, and the tax value is only $68k (about half and half land and building).

That is probably the easiest thing for a SF inquirer to understand.  

This is how I feel but I was going to be nice and refund half of the deposit because my husband and I can do a lot of the work and cut the cost.

The house was originally a 2 bed 1 bath, but a 350 sq ft addition was put on (with the half bath).

Well, the easiest thing is not put $50k down.

2 bedrooms are pretty rare in that area unless its half a duplex or a townhome.