I would ask for tax returns for the past several years to get a better handle on income and expenses. Would also press them to carry back 100% rather than just 50%....if they're desperate enough they may just go for it. Chances of someone (especially a newbie to this particular biz) getting financed through a bank are fairly slim at this point. You may even be able to give them a higher purchase price if they carry the whole note at a decent interest rate....

Another BIG consideration is the environmental aspects of purchasing a gas station. What is the condition of the tanks in the ground? How long have they been there? I wouldn't consider an older gas station without a thorough enviro assessment. And yes, they can be very expensive.