I wouldn't even begin to make on offer until you get him interested in the idea of selling, you will need to see his Financial Statements,
I won't pretend to know anything about the restaurant business, but I have to ask, what do you expect the profits as a % of sales to be?
Spliting profits of 10% (assuming its even that high) 4 ways is 20-25K per year
what type of salary would you be making?
if profits are high enough, perhaps the business will finance its self , like buying his business with his own money
I purchased an existing 500K in sales business this past summer, and the purchase is financed by its profits. my downpayment was 10K
you have to see the financials before you can even think of making an offer.
What is the loyalty to the owner, do people come to the restaurant because he owns it or because the food is fantastic. and will they keep coming back after he's gone