Phoenix - Very big area so you'll need to look at what's nearby. 

You want to be in an area that's convenient and has popular attractions nearby.

A quick look nearby rentals are $475, $500, & $395.

Location, location, location plus current zoning, availabilty of comparable land in a 5 mile radius, availability of utilities (on site or nearby), is it a pad site or raw land or demolition and prep is needed etc will determine the asking price which could be entirely arbitrary.

You can find upcoming nearby meetups here https://www.biggerpockets.com/forums/521-events-and-happenings

@Taylor Cain Howdy, I am nearby and can help answer your questions also.

I have identified a town nearby that wants to welcome development. 

I can't say if this zip code is superior to others nearby but I can say that we funded a few successful BRRRRs in the 32641 last year. 

They scheduled a time to talk and during the call, I could tell that the property was distressed and under-capitalized, and that the owner was open to selling because he wanted to get into short-term rentals in a nearby city.Prior to our appointment, I researched everything I could find about the owner online.

Then rent will be forecasted by Appraiser by survey of nearby rehabbed 2 unit propertie's monthly rents.