1) Guaranteed Rankings
In today's search engine marketplace anyone (and I mean anyone) can guarantee a top ranking on a top search engine through one of two methods. First, the broadcast exposure of "pay per click" listings allows any webmaster to bid for top placement for any keyword imaginable. This strategy yields only short-term results however, because once the advertiser stops bidding the client's site is immediately removed from the top spot. A second method for obtaining a guaranteed top ranking is by targeting keywords that are noncompetitive and seldom searched.
The most valuable service of a reputable search engine optimization/marketing firm is not the ability to rank a website well for a given set of keywords, but the ability to identify keywords for which top rankings will benefit the client.
2) Submit to 100+ Search Engines (Or More!)
Though there may be several thousand search engines around the world, only a few have the reputation, traffic, and technology to deliver significant levels of targeted visitors to your site. In reality, there are probably only a dozen English-language search engines to submit to, from which other top players receive their results.
For example, you may find a service willing to submit your website to 100 top search engines for one low monthly price - their submission list is filled with reputable sites such as Google, AOL, Netscape, iWon, Yahoo, etc. - there's only one catch, all of these mentioned engines use the same index. The company is not really submitting your site to all of these engines, just one, plus, monthly submissions have no added value in this case. Once indexed, most spidering engines will continue to revisit your site automatically, regardless of whether or not you "resubmit" on a continuing basis.
3) Fixed Pricing
Search engine optimization is a professional marketing service. How can a company offer an effective online marketing solution for your website without first reviewing your company's industry or your website's content, structure, or competition? Search engine optimization is not like selling ad space on network television where a standard product is offered to any company who can come up with the cash to purchase the media.
SEO firms are more like the company that produces the ad, where services vary based on the needs and goals of the client.