Door knock, drive for dollars and then cold call (you'll still have to pay for skip tracing).

Whatever you choose to do, mailers, cold calling, drive for dollars, just know that most people try it, don't have instant success, and then quit. 

Nevertheless, basically, the FHA wants to know that the property you’re about to purchase will be self-sustaining and that the income brought in from rent will cover the mortgage. 

But since I don’t know what city you live in, you might need to ask yourself real quick, if the market size and activity level could sustain some ups and downs, especially since both you and your girlfriend are agents.

Your running $58, which I will assume your average is a 10 x 10, but this is only about 1/3 the Ann Arbor rate for Drive up access.   

Hey Simon,As many say, your first investment purchase will probably not be your best, so don't drive yourself too crazy on the first one.

I just spent Saturday driving for dollars and two of the places I identified where owned my mom & pop investors with over 50 properties.

There are plenty of investment pockets in Florida that would suit your budget, but yeah, South Florida can be high overall, but there's plenty within driving distance that can work.

Related to last item but from a sustaining perspective, next item is providing residential housing, even with the use of a PM, is not passive.  

See if zoning will allow shared drives, then take the parcels and re-plat and subdivide into 4 lots.Spend $10,000 on everything.