The only way I would consider what you are proposing is if the equity from your coop is enough to place enough of  downpayment (think 50% of purchase price) on a small multifamily (think 3-4 family) so that the income from the new property is enough to cover all expenses of the new property as well as the loan (or a significant percentage thereof) on your personal residence.It's a gamble that can break you or be the beginnings of your real estate portfolio.

Use a syndication tool such as Zillow Rent Manager to syndicate your ad all over the web. 

The Flipster web site list a lot of benefits for only $97/mth and the way his site and funnel is laid out there is no other cost showing but there is always the up sale pages after the initial buy so Buyer beware and always review the actual website before you buy.

Ours were plausible triplexes BUT there was a bit of a gamble involved.

I'm only given 80 web leads a month by my brokerage and when it comes to prospecting, I want it to be the last resort to knock doors.

Very few have been operated as a business...most are, at best, a hobby, where the Owner enjoys doing handyman work (often of dubious quality), at worst, an absolute "investment" Gamble, with no regard for tenants, laws, or much of anything but spending the absolute minimum while collecting the most money possible until their "cash cow" implodes.

It also seems like a huge gamble to operate if I don't know quite for sure the variables involved to make a place have 33% occupancy rate on the year vs 75% occupancy rate on the year.

Stocks is gambling. 

That was just a quick and dirty statistic run, without filtering by rental class type, etc.Some data pulled from the web shows job growth expected to grow at around 37% in the future.

Realtors/Brokers: Does any of you consider valuable a unique website that differentiates from others, instead of using the same templates that can be found online by web/SEO companies?