If you ask Google if an SEO company can guarantee you a top organic ranking, they'll tell you that the answer is, "no." A lot of realtors wonder why SEO companies can't guarantee them a top spot. Let me shed a little light on the situation. It's difficult to guarantee that over which you have limited control. It's for this reason that many ethical SEO companies don't offer any type of SEO ranking guarantees.
Regardless of what they say during their sales presentation or what information is contained in their literature, no SEO company has control over Google's ranking algorithm. No SEO company knows Google's ranking algorithm either. There goes control over one variable required to guarantee a website a top organic ranking.
There are a limited number of organic search listings on the first page of Google - typically about 10 - 15. What is required for your website to rank well organically depends - to a large extent - on what your competitors are doing with respect to SEO. And it's not just other local realtors you have to be concerned with - lead generation websites, association websites and various other directories are all gunning for your search real estate!
No SEO company can control what your competitors may decide to do tomorrow. If you've signed on to pay $1,000 per month for SEO and suddenly 20 other local realtors start investing $5,000 per month, it's going to be difficult for you to keep up - even if your SEO company has a superior formula.
In some ways, SEO and Pay Per Click are becoming similar. The one that pays the most wins. With Pay Per Click, you pay "per click" where as with SEO, it's sort of "all you can eat" for one monthly fee. As more realtors become familiar with these strategies, the cost (of both) is going to go UP. That's a fact.
The only way an SEO company can guarantee results is to offer some type of financial incentive - i.e. "We'll get you ranked or your money back." Google can't say that these types of guarantees are impossible. Any SEO company can offer something back or something at no charge if you don't get what you hired them to achieve.