Hello! and welcome to the site!
So... my first question would be how much you plan on making per property? I ask this because selling turnkey properties is extremely difficult. And your operator is correct with not wanting them on the MLS. The MLS is for local realtors and there clients, where as turnkey properties are more for out of state investors and your personal network of investors.
The first thing I would say is you have to be an absolute expert in the area that you are selling. So if your selling Memphis you need to know more about that city than the locals do. If you don't your potential buyers will eat you alive with questions about population growth, local economies, demographics of neighborhoods and much more.
Next is knowing the property management systems inside and out. What is the management fee, is there a lease up fee, what is your vacancy rate, when is rent late and whats the late fee, etc etc... Any investor thats savvy enough to succeed within a TK system will be asking all these questions and many more.
Cap rates... you HAVE to understand capitalization rates and how they work. Can you explain the benefits of X property that has a 7% cap rate VS. Y property that has an 11% cap rate...? Essentially you need to understand the ROI associated with real estate (and Ideally investing in general) and how cap rates, equity, appreciation, and liquidity all play different roles. ..and when you advertise your properties be sure to quote the most accurate numbers you can. Exaggerating your numbers might seem tempting because lots of TK advertisers do this but in the long run honesty is the best policy.
In your post you ask if there is a website where you can find TK buyers. There is! You found it! BP has a ton of investors looking for passive income. But you can't just throw up an ad in the market place and expect buyers to flock to your property. Well... you really can't do that until you upgrade to a Plus or Pro account... but what I was getting at is you have to build trust with your buyers before any one will even pay attention to your properties.
You need to be confident and sincere when pitching a turnkey property. Here is the test: Would you feel confident selling this deal to your Mom? Grandmother? Brother? Best Friend? etc... or better yet would YOU hold this property as a rental? If you wouldn't hold a deal your self then I wouldn't try to sell it turnkey... especially to a BP member.