I know someone who picked up a stainless gas BBQ free from the curb in front of someone's house. It was in great condition, the burners and grills looked like it had hardly been used. New, it would have been in the $1000-2000 range. What was wrong with it? All it needed was a new AA battery for the ignitor!
My experience with gas BBQs is that the ignitor is usually the first thing to go. Usually, again in my experience, it happens due to corrosion of the ignitor itself. My solution is usually just to use a match, I find that the ignitor stops working so quickly that it's not worth replacing.
Replacing the grills, heat spreader, and burners however makes a lot of sense and can make an old BBQ virtually new again.
