How long is a piece of string? The cost of an installation by a professional fitter can vary massively and depends upon the amount of work involved (both expected and relatively unexpected) and the quality and amount of materials being used.
Some projects may be more of a refresh for example, replacing a few units, new doors, installing an island unit, whilst others are full scale refurbishments which include installation design and planning and the co-ordination of many skilled tradesmen for example, plumbers, tilers, plasterers, joiners and decorators. Most kitchen installations are refurbishment rather than refresh and include the gutting and disposing of an existing kitchen, the installation of new units and appliances, the fitting of flooring, tiling and lighting and then decorating.
Professional kitchen fitters specialise in the installation of kitchens and bring the equipment and experience necessary to get the best results possible. You can lower the kitchen fitting cost by trying to do some the work yourself but of course you risk damage due to faulty installation which may cost more to put right later on. If you are confident with electrics or a paintbrush then these maybe some of the areas you can save costs on. However, if your kitchen installation includes the setup of a gas cooker you should always look to employ the services of a gas registered fitter.
Using your kitchen retailer's own installers should be beneficial in terms of cost as the supplier may charge you less as you have also purchased the kitchen from them. Certainly an opportunity for negotiation! Generally you should request at least three quotes from different installers before you make up your mind who to use.