One alternative or supplement to SEO is Paid Search, or Pay-per-click (PPC) advertising. With PPC we bid on search terms, saying how much we are willing to spend per click for each term. The more competitive a term (how many people are searching) the higher the bid required to rank highly for that term. Costs per click can range anywhere from pennies up to $100. Most of the keywords we have purchased for our clients have averaged under $1.50.
We often use PPC campaigns to augment SEO. In some cases keywords are so competitive that it is virtually impossible to optimize for them without adding dozens of pages of new content. In those cases, it is much more cost effective to rely on PPC to reach people searching those terms.
You can spend as little or as much you like on a PPC campaign by setting a maximum amount to be spent each day. Sponsored listings are a sure-fire way to get clicks and increase traffic on your site. One major benefit of sponsored listings is you are only paying for those that actually click on or visit your site. It's like buying a yellow pages ad but only paying for those people that actually call you. Even most banner ads are priced by the number of people who view your ad, not by the number that visit your site.