The short answer is that it doesn't have to be unless you're facing very heavy opposition. Search Engine Optimisation (SEO) is based largely on the text content of your website, and as long as you can edit your site content you can control it's SEO.
Your ranking in search engines comes down to how well the search engine favours your site over your competition. So the amount of effort required to reach the top is determined by how hard your competitors optimise their sites.
Search Engine Optimisation is relatively straight forward, and with a basic understanding you can really turn your website around. SEO does take time though, both to plan what you're going to do and to go through each page and work on it.
How can you keep the costs of SEO down?
Quite simply you can do a good chunk of the work yourself. That said it's important that you understand what you are doing, and that the advice you have is up to date. Google and other search engines constantly update their algorithms so people can't game the system. This means that older tricks to rank well can be penalised today.
If you're serious about doing your SEO properly spending a few hours reviewing your website with SEO experts like Webbed FeetUK will pay dividends. You'll be able to work out a good strategy so you know where to spend your time to get the best results. And you can be sure that your optimisation is actually going to benefit your website.
Once you have a strategy in place the majority of your time will be spent revising your existing content and creating new content targeted at specific search terms. By ensuring pages are carefully focussed to individual search terms, that your pages titles are optimised and that your site is well interlinked you will drastically improve the SEO of your site.
This is not to say that you won't need a technical SEO expert like us to make some changes to your site as some aspects require knowledge of coding. Also you may find if you're using a system like WordPress you won't be able to fully optimise your site even with an SEO plugin.
To start learning about SEO you should take a look at our blog articles on SEO we've written a whole library on how to improve your websites SEO.
Whatever your budget, Webbed FeetUK will be able to find the most effective solution for getting your site found on Google.