Be concerned with how you are perceived. You cannot put a dollar value on access to high corporate executives. There are two kinds of amateur inventors, the paranoid and the more paranoid. Approach only major, blue chip companies, and don't allow the paranoia of being ripped off control. Companies that rely upon inventors, do not go around stealing ideas.
Royalties are a pass along expense.
Don't take your idea too seriously, either. The world will probably survive without your idea. Industry will probably survive without your idea. You may need it to survive, but no one else does. It is a mistake to think anything is made overnight except for baked goods and newspapers.