SEO is vital for every business to be found but that doesn't mean you have to pay someone to do it.
If you think customer first and write a blog or articles on your site you will naturally use the words that people will be searching for. This is the sort of thing that Google et al are looking for and is therefore SEO.
Whilst SEO advice and activity would undoubtedly be useful it is not a one-off cost and has to be done constantly. Some 'experts' just want you to pay for traffic using Pay Per Click (PPC) - the benefit stops as soon as you stop paying.
If you decide to engage an expert walk away from anyone who promises you will on the first page of Google - the results are influenced by where you live, what else you have searched for previously as well. Also some of them mean pay them to put on PPC and you will appear on page one when your advert gets shown (not all the time by the way).
If you break down your customers into small niches and write for just that person - eg if you sell dog coats you write an article about keeping small dogs warm or even further one on keeping small short hair dogs warm and another on keeping small long hair dogs warm etc. Each article or blog entry is targetted to one type of customer (and therefore one keyword phrase)
Make sure you don't duplicate your content anywhere. Never pay for links.
This is worth reading https://moz.com/beginners-guide-to-seo
There is lots of useful advice here https://moz.com/beginners-guide-to-seo
Before you drive content you need to check whether your site will convert visitors into customer so you really need Conversion optimisation. Start by asking friends who haven't seen the site to pretend to be a customer and go through a buying journey - ask them to be brutal about what think. You can fix lots of problems for free this way.
Good luck!
