I personally think that spending money on gaden decoration is such a waste. Where is the fun in creating a garden, if you let some unknown guys to do the job? There are many ways to design your garden. For example, one of my recent works - Zen Garden. It is a quick and easy DIY project. Just some extra imagination will do the job.
Well I'd employ a designer if I could. I'd love to have the hard landscaping in my garden done really well as a framework for the plants. I'd like plant suggestions, too, from a real expert, though I'd want to choose and plant them myself. That would be a much more manageable task than the one I have - taking a garden that was hideously and amateurishly entirely paved by its previous owner and take everything out and start again with little spare money, because we were also renovating the house.