I was recently told by a company that they were paying (what they considered to be) a bargain rate of around $10 per day to stay on top of a major search engine. The CEO of the company was quite pleased when the employee that had suggested the expenditure proved that, sure enough, the money was well spent, there they were right on top of the search for those exact keywords.
There are a few points to consider if your company is planning to throw marketing money at a major search engine. First, there is more than one search provider and each handles searches a little bit differently. You can position your company on one search provider and it won't make a bit of a difference on the others. Often customers don't realize they are using Google over Bing over Yahoo and don't care.
Secondly, your company can hit the top without the extra outlay and search optimization should be part of the cost of the web design and deployment and strategy.
Or you can continue to pay a princely sum to the search engines...