I have found HELOCs that range from 70% LTV upwards, but they vary from lender to lender. 

After grad school I anticipate starting salary of 300k+, but will have 200k student loans which will only delay/limit me from starting my real estate investing journey.I have enough saved for up to 15% down payment on a fourplex around 450k, but dont want to go hard money lender/dscr as they are currently in 7-9% range.

In that 800k-1M price range you may want to consider less cash flow for 1-3 years because in the right areas the rents and value appreciation is kicking in faster. 

Now, for the sake of completeness, I have to add that my deals were back in the 2015-2017 range, so things may have changed in the meantime (I doubt they have). 

So that smells fishy..The vast majority of real estate agents do not own a rental property and have very little knowledge in that field.

Looking at the listings, it seems like there are a lot of properties that are competing around the same price range.

To top it off, the market was more within my price range, and I started to see numbers that I was excited about.I started looking in Ohio in December.

As you can see below, the information provided by Rentometer is nowhere near the actual rent.To show what a difference the broad range of Rentometer predictions has on return calculations, I used Rentometer to estimate the rent for another property.

I am looking at a mixed use building in the 6 to 12 unit range in an expensive area of the country.

The vast majority of investors do not grow massive portfolios, so keeping it at a handful of roofs is pretty typical and just fine.