Back when we started and land was cheap we built a few spec houses and did ok.

about the condition of the property, if it truly is this much of a "steal", and likely hesitate to pull the trigger. 2) Take a risk on a property in the city near me (cheap prices, high turnover, poor schools, low income), which is not a great city for real estate, that I can buy entirely using my HELOC.

Cheap.  10k or less. 

I planned on renting a cheap place for myself but buy investments to get passive income. 

The house were wanting to buy is a major fixer upper deal and is going to be completely as-is, And is extremely cheap (less than the assessment value on just the land) we may even just buy it with cash and finance it later to get the cash out.

Does anyone out there know of a free or cheap online service that their tenants can pay rent and it deposits into your account?

That's not to mention the tenant headaches and fact that you would need to stack up 50+ cheap units each cash flowing a few hundred a month (which looks high on a percentage basis) to start to get meaningful cash flow going, which very quickly starts to resemble earned income from a job more than passive income from investment.

Here's a BP post on "driving for dollars" -- a super cheap way to find distressed and abandoned properties if that's your goal: https://www.biggerpockets.com/renewsblog/2013/05/03/driving-for-dollars-bible-part-1/.

From that perspective, $750 is cheap.

It takes some studying and that pain, but otherwise it's cheap to maintain.