Some sellers want to wait and see what the market will yield at the end of the lease or want the option price to be $30k - $40k above the retail price today.How can you get the seller to agree upon a pre-determined option price at today's market price?

Predetermined late fees are deemed illegal and any such fee must be justified by the landlord as a real cost.

@Robert JensenThat sounds arbitrary to evaluate you a predetermined cost.  

This can also be used as a short term basis if you're flipping the property (any amount from the sell minus the predetermined price goes to you.) 

The idea is that you pay an upfront option fee (1 to 10% depending on the owners market/motivation/competition) to purchase the house later at a predetermined price while you rent it, usually at slightly higher market rents (& you may be given rent credits for monthly on time payments which will be used for your closing costs at time of purchase).  

My thought would be that I would bring a relatively small cash contribution but give most of the overall appreciation to the flipper, in exchange for the experience/knowledge that I would be earning and the promise to be the guaranteed first offer with predetermined price range when going to refi (maybe even with private hard money on family-member-terms).

More Financing options Lease-purchase agreements: A lease-purchase agreement allows the buyer to rent the property for a set period of time, during which they have the option to purchase the property at a predetermined price.

Investor buys home with pre-determined sale price to tenant-resident (ultimate home owner) with targeted purchase of 6 months to 3 years.  

Automatically add money to an S&P 500 ETF into your Roth at predetermined periods spread throughout the year to surf off both gains and losses.

People simply won't easily buy a house with previous hystory of crumbling foundation even if it is fixed... or "claimed" to be fixed.The 70% rule also doesn't account for the projected time it takes to flip a house.And no... your predetermined "holding cost" incorporated in your 70% rule is not it.The 70% rule is a death trap and is a sure way to derail your business.Also, if we are both interested in the same property, and you give a 70% offer, you will ALWAYS be beat by me that will ACTUALLY give the highest possible offer I can make. 70% rule focuses on being "safe" and will have the effect of not getting many deals.The right method focuses on property determined risk analysis to leverage "being safe" with the amount of allowable profit (for that safety margin).