If you own your own business then you will need to think carefully about your marketing. It is easy to let marketing get forgotten about especially if you have a lot of work coming in, but not doing any marketing could leave you high and dry with no work.
Marketing doesn’t have to cost the earth, although often you do get out of it what you put in. If you are willing to spend a bit of your own time on marketing then you could save money on paying someone else to do it, but I would only do this on the advice of an expert. Many marketing companies are happy and want you to get involved and provide information that they can use in their marketing strategy for you, but will need to be able to have some control over what gets distributed where. You could always start with a small budget and increase it as your work increases.