Hi @Scott Granberry - HELOC is an excellent choice in financing deals, you can also use your IRA through a company such as Quest IRA to fund the entire deal or just a portion of the deal. 

Being in a bad part of town usually means the quality of tenants won't be that high.

I had been holding on to this money for a couple of years hoping to get a multifamily , but the prices in NYC are just crazy right now, I feel that we're in a bit of a bubble, and it came down to a choice between keeping it in a 1 year CD and generating 4K,or paying off my mortgage and saving 8K/year.

@Patrick Vos, I don't think its a bad idea at all!

I don't want to waste anyone's time and I don't want to start off with a bad reputation. 

Not great, but not bad either. 

On those websites, a listing that old is either the owner just trying to see what they could get or it’s a bad property (either economically or physically).

On one hand you want to be humane, but on the other hand bad tenants can make your life miserable chasing them for a few hundred bucks.

@Bob Starlin When Mark Twain said 'Good decisions comes from experience and experience comes from bad decisions' he must have been thinking about investing in MF-we will never know for sure.

The rent will need to be a 'fair-market' rent, i.e. is it equivalent to what a non-related party would pay, or a similar rate as other SFR's in the area are charging.Additionally, for further proof of intent as an investment, it is never a bad idea to have a lease agreement with your tenant, whomever they may be.