Is this Off Plan investment good or bad?

[Eamon Heggarty]

"Off Plan" i am referring to a building that hasnt be built but is in the construction phase.

1 Bed apartment - 550sf

Fully furnished to a high spec

Build period - 24months

Rental Package - I am guaranteed 5 years of rental income

Cost - $120,000 (due to it being off plan this price is already 20% under current market value and not 24months from now market value)

Rent per month - $650

Management fee - 8%

Mortgage (after build is complete) 70% - $350/month

Payment scheme - 30% deposit is covered over the 24 months by my own personal payments, therefore 30% of 120,000 = $36,000. Then $36,000/24=$1500/month payment.

I know this is a unique way of purchasing property but i a 99% sure i am going to make this deal/ Does anyone have any thought on it and if its good or bad please :D 

Thanks