Build a list of things that you will be addressing in the Purchase Offer and decide how you want each of them handled. Now you will not be able to cover EVERY scenario but you will be much further ahead (and prepared) when it comes to crunch time. What do you do then? Present the offer to the seller. Make sure you have an ending day and time for your offer to expire. You do NOT want the seller thinking this over for too long.
HOW VALID, OR OTHERWISE, ARE THESE USUAL RATIONALE BY SELLERS OR THEIR AGENTS? Ironically, while oil sellers and their agents frequently demand that prospective "serious" buyers involved in crude oil transactions should first offer an LOI, the buyers, on the other hand, are not generally enamored of that idea.