Multi-unit Property Valuation: Cap Rate vs Property Location Comp

[Cedrick Layton]

I am new to evaluating properties for wholesale. The first property I started working is a multi-unit property located in a very hot area in Atlanta. When I started doing my initial analysis it seems that the value based on the Cap Rate and NOI put the property at a significantly lower value than it's surrounding SF properties. Because I am just working on examples from a list and don't have a deal in place I will share the detials.

Property Address: 642 Seminole Ave NE Atlanta, GA, 30307

Specs: 3 bed 3.5 Bath 

Units: 3

Rentometer for 1bed/1bath in area - $1,236

Gross yearly rent - $44,500

Property taxes - $8,700

Vacancy Rate for Atlanta - 6.1%

Based on these numbers and the 50% rule for expenses, the property value would be around $400k. I used this formula and rounded up to get that figure. NOI/Area Cap Rate = Property Value. If I look at surrounding properties that are single-family properties the minimum for a 3 bed, their value is at minimum $700k. Should these single-family comparables be completely ignored or does it indicate an error in my calculations?