I read it everywhere that buying into quantity (think Class C multi) is like buying yourself a full time job....

With a modest amount of capital, one can be VERY selective in pursuing only the deals with the greatest potential, and run a "quality" based shop, rather than a "quantity" based shop.

I am wondering if anyone knows some 'trending' areas for high-quantity real estate flips?

I am a known quantity on the funding side  so when I say go they go. and this is were I see most that THINK they want to wholesale miss the entire point of being a RE mover and shaker you need MONEY and or MONEY connections.. if you want long term viable business.

Once you get an idea of the quantity then you can back into the price.

BUT it's very beneficial to both you and your GC.Providing a good Scope of Work along with approximate quantities and counts for main tasks will allow various GCs price your project more precisely.  

I don't know the answer in this case but would advise to look at the class, stability, of the tenant base and correspondingly the work involved in being a landlord there and consistency (not just quantity) of income and expenses compared to the more expensive neighborhoods.

Records maintained for a series that reasonably identify its assets, including by specific listing, category, type, quantity, computational or allocational formula or procedure (including a percentage or share of any asset or assets) or by any other method where the identity of such assets is objectively determinable, will be deemed to account for the assets associated with such series separately from the other assets of the limited liability company, or any other series thereof.

Anyone found a good source for larger quantities of LVT?  

Yes we have different mindsets but that doesn’t mean that we can’t complement each other when we figure out how to use our past experiences together in harmony.