On average I’d say a duplex is 150 a month in water alone, and sewer is probably 80.

Where demand does not outstrip supply.It's quite common in many markets to be able to buy, say, a duplex for $80k, that rents @$800/m. ie. 2%.

What should I say?As

But I don’t know for sure and not ashamed to admit that :) I should also say as Big Dan Zitofsky (nice seeing him here by the way) mentioned partials, I saw a presentation in California by Rob Happe on partials that looked very interesting but I digress.....Really amazing how two words “note buying” has so many offshoots.

I say a couple because anybody can show up once, but is it a business practice? 

Real estate is, as I like to say, a get rich slow scheme.

How much would it cost to build say, a 1,200 sqft home on .25 of an acres over there?

I would put it on the same playing field as...say...a public restroom at a rural gas station... 

Rates will be going up so financing will be more expensive in say a year.

Others will say as little as possible, I like doing 20 percent as it helps limit your risk some.