If you have a specific area you're targeting your agent could send out a letter to the owners of properties in the area indicating that he has a pre-approved buyer looking for properties just like theirs.

However, what they don't mention is that month-to-month is subject to rent increases (I confirmed with the leasing office after receiving the letter).

I'm new to wholesaling and I understand the concept of driving for dollars,  mailing out letters or post cards, spending tons of money on postage, or putting up bandit signs.

Send a letter to the HOA rather than call. 

style="-webkit-font-smoothing: antialiased; margin: 0px; padding: 0px; border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-weight: 400; font-stretch: inherit; font-size: 1rem; line-height: 22px; font-family: "open sans", sans-serif; vertical-align: baseline; position: relative; overflow: hidden; color: rgb(52, 65, 77); letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; height: 1288px;">BRRRR and a TIP OF THE DAY : )RUN YOUR NUMBERS!!!!

You may be able to back after them for your costs in straightening this out.Did you get any letters of indemnification from that seller and tenants that stated if there was a security deposit, last months rent, who was in the apartment etc etc?

Granted, the rest of the block were larger single family homes...

If you're going to use an LLC, you'll need the EIN letter, W9, certificate of good standing, articles of formation and the operating agreement. 

When you fail to send the money back or a letter explaining deductions, you give up your rights to the money.

Get a letter from your employer showing your wage, start date and type of employment (full time hopefully).