I also have some administrative experience in rentals, lease preparation, and collections.

I think buying is a solid choice as long as you make some good contacts while your hear, most importantly a good property manager but also try to find a good handyman for service calls, a good cleaner, good yard person, ect.  

Their lease will end by March 31, 2018.

I think there are few different ways to do this (e.g: lease option, subject to, land contract) Check out this article to get started then search the individual tactics in the BP search bar to get more info. https://www.biggerpockets.com/renewsblog/2011/07/20/seller-financing-3-kinds/

We put a tenant with a lease option.

Is this one lease that all three of them sign, or three leases, one for each of them.If one of the three does not pay, then what?

On the lease it is not specified as a "move-in fee" but only referred to as the non-refundable portion of the deposit.

Should I just hold out until I have enough cash to buy a cleaner property that will attract decent tennants, or should I actually consider buying a $30K property in a horrible neighboorhood since I can buy now, and POTENTIALLY start cash flowing now?

Also, learn how to buy properties with seller financing or Subject To, or with leases and options.

It's not the prettiest thing but throws off decent cash flow for the investment.The property is just under 3 acres with 6 leased lots with tenant-owned homes and a 2/1 block building.