The "market +/-$" depending on lease duration sounds like a good idea.

@Andrew Schrader you can also get some window screens that extend horizontally to stick in your windows with no screens.

We got it under contract, but the inspection determined we would have to replace a garage/basement wall and we had to extend the deadline to commit until this Friday to get some bids for repairs.

I'll pay you $YY cash towards <insert-local-inexpensive-motel-here> for the duration of the renovation!"

Thanks for reading and any advice you can extend ! 

Thanks for reading and any advice you can extend ! 

We got it under contract, but the inspection determined we would have to replace a garage/basement wall and we had to extend the deadline to commit until this Friday to get some bids for repairs.We have reached the seller's bottom dollar of $280k ($15k below listing).

I would recommend keeping your older ones open to extend the average of the age of your credit and increase your available credit but keep the amount owed to a very low percentage of your credit limits such as less than 15%.

If a purchase contract is not possible at this moment, are there other ways to at least have some sort of an agreement in the event he decides to sell in the future, some sort of a "Buyer's right of first refusal to purchase" for a set price and duration that may work to my advantage and still give the seller the freedom to not sell?

A month-to-month lease automatically extends.