We want to take it to a higher level and do about 9-10 flips/year.  

You need to figure out what level of finishes are expected in the area and estimate the rehab based upon those expectations.

Still, the question most of us want answered, at any level of investing, is "How can I duplicate that?!?"

I'm a California native, ex-Manhattanite, transplanted to New Zealand.

I can tell you from a lot of personal experience that it can be a great cash creator and can help you create wealth like nothing else I've ever seen (especially for the risk level that a good area can provide). 

It is in pretty bad disrepair, with the biggest and most obvious issue being the mold that is in every room of the entire lower level of the home (it's a 5BR, 2BA (~2000 sq ft) split level - lower level has one bath, living area, 2BR, storage space and utility room).

We have investors from all levels- including those who are just getting started.

One of our clients recently used, HomeSmart Inspections and I was extremely impressed by the level of service they provided. 

Leverage the cash by safely purchasing the multifamily property/properties that will provide a return you are comfortable receiving at a risk level you can stomach.Tough question- you may also consider the FHA program: https://www.biggerpockets.com/renewsblog/2012/11/08/fha-loan-multi-family-investment-strategy/

It will depend on level of finishes you.