I paid the landlord/vendor a fee {the option price} for the right to purchase the property at a predetermined price {the strike price} within a given timeframe (2 years in that case).

Basically you use a split the difference on your pre-determined max bid.

I've read before about L/Os that set up a down payment, a monthly rent, a monthly addition to the down payment (forced savings) and then purchase for a predetermined price.

Determining rents is pretty simple...and knowing whether the rents can be forced higher through upgrading the units is pretty straightforward...as is determining whether this building (an 8-unit) will ever appreciate more than a pre-determined price.

Don't get too caught up with the price, of course it is very important to look at but it is not the primary predetermining factor that makes a deal a good deal. 

I'm thinking of working out a deal with a PM where I do anything that falls into any predetermined categories of maintenance and they handle "tenant stuff"  and major issues. 

I never predetermine my exit strategy on any deal, meaning I don't look at deals as this one is a wholesale, that one is a fix-flip, and that one is one I'm going to hold as rental.

Perhaps I am just lucky, but I have a team member I can trust and more often than not, my pre-determined exit price is the same as what I am given (which gives me confidence that we both did our numbers accurately).

If, at the end of the option period you choose to do so you can purchase the property at a predetermined price OR lose the downpayment and supplemental payments. 

SEC has predetermined compliance is considered a private placement exempt from SEC registration.