Basicly you ask do I do it myself Having been a design engineer for more than 50 years now into my dotage I think I have been asked this question a million times and I don't think there is an easy answer Chris021 ! It depends on the answers to several questions.
1 Is it a commercial project ?
2 How urgent is the project?
3 do you have the skills and experience to carry out the project alone?
4 How much do yo value your time ?
5 Are you prepared to expend the resources to pay a consultancy to realize your project?

Having answered these questions you will be in a position to decide for yourself which way to go.
don't under estimate the design time required whether you DIY or contract the job, I think every one has met bad hurried design - at one time China was famous for it like the coffee bot which always made a mess when pouring because the spout was above the lid!!