Too good to be True?

[Eric Hall]

I am analyzing a potential deal and I really like some help figuring out what I am missing.  It seems like $140,000 in built in equity seems to good to be true.

New Build Duplex

Kent, WA - 3,155 sg. ft. 3 BR/2 BA/2 Car Garage

Land: 40,000

Cost to build (from Reality Custom Homes): 195,000

Site Prep: 10,000 (relatively flat land, utilities all easily accessible) 

Permits and fees: 20,000

Landscaping, Fence, Driveway: 15,000

Upgrades: 20,000

Closing Fees:10,000

Total Cost: $310,000

Estimated Appraised Value: $450,000 (based on the sale of nearby townhouse w/similar stats)  I believe duplexes are appraised as separate units and then have their values combined. 

Estimated Rent: 2 x $1800 = $3,600

It fits the 1% rule, cash out around $30,000, $140,000 in equity built in.  What am I missing? What questions do I need to be asking?  Do my estimates seem reasonable?  I am currently trying to figure out zoning with the City of Kent.

Thanks for any feedback.