It took me over 15 years working in the corporate world to come to that same conclusion so congrats on getting their sooner.Here's what I will tell you....wholesaling is a sales and marketing business.

I'm the sole member of the LLC and it has no debt and no other assets besides the rental property package for sale.

It sounds like you have undercut the sellers expected sales return from $180k to $150k.

Initial plan is to acquire a 4-plex and then move on from there into potentially flipping or additional multi-unit properties.

Are you the type who likes sales?  

Virginia members:We recently acquired a property for a rehab project that has tenants in it. 

If she had not called, I would not have even known it was for sale until it was too late.  

(Make sure you are including your closing costs on purchase and sale to compute.)  5% vacancy is probably unrealistically low unless there are long-term tenants (which often means the rents are below-market).

I would like to acquire another 3-6 more houses, so I could quit my job and become a full time investor/landlord.  

The easiest way in my opinion is to make the sale for the seller as easy as possible so he's inclined to sell it to you.