Or are they typically sold individually?

As others have mentioned, learn the fundamentals and analyze each property individually.

Keep in mind that each individual property has different utility bills (due to energy efficiency, possible water leaks, square footage, number of tenants, etc)  Calling the utility company will at least give you a starting point. 

I have called several individuals in San Antonio from homes I have found in Craigslist but so far I have not been able to pin a house down. 

I'd like to connect with anybody on here, and especially the individuals from San Antonio and nearby areas.

I would love to network with other individuals around the area that understand creative real estate investing & other wholesalers as well.

Is it recommended to wholesale individual apartment units?

It is awesome to connect with other like minded individuals.

In short, if you want a seller-carryback note created on or after January 1, 2014, if it is a private individual, trust, or estate, then ask them to sign an affidavit saying that they have not done more than three in a 12-month period and how many of them had balloons.

. === here's the Calif Form, observe, it's a Proof of Service, not a Notarization === Proof Of Service I, the undersigned declare under penalty of perjury, that I served this Notice to Pay Rent or Quit, of which this is a true copy, on the above-mentioned Tenant in Possession in the manner(s) indicated below; [ ] On ____________________, 19____, I handed the Notice to the tenant. [ ] I handed the Notice to a person of suitable age and discretion at the tenant’s residence/business on ____________________, 19____. [ ] I posted the Notice in a conspicuous place at the tenant’s residence on __________________________, 19____, [ ] I sent by certified mail a true copy of the Notice to the tenant at this place of residence on ____________________, 19____, Executed ____________________, at _______________ By ____________________________________________