Web design and graphic design work should be of a certain standard if they are going to be associated with your business. This means you need to take on the associated costs, as it is going to work in your favour in the long run – nobody wants a unprofessional or shoddy-looking website.
At the same time, you don’t want to be paying more than you need to for a website, brochure, catalogue, posters or similar. Ask a few different agencies for a ballpark figure. It may take a while to get quotes as many good agencies will want you to go in and speak to them. It is very much worth doing this though, because you will gain a much better understanding of what you will get for your money. Some agencies might simply create a design template, whilst others will build a bespoke design that works around you. Talk it through to understand what your money gets you.