A lot of people come up with ideas for new products, and while most are, quite frankly, crap, there are always a few gems. The problem is that, because these people who come up with these ideas aren’t usually design-focussed or without training in it at least, these ‘gems’ of ideas, are diamonds in the rough.
Developing an idea for a product from these initial stages is the remit of product design consultants, and is definitely a service which people who think they have a profitable idea should invest in. Product design consultancy has a number of fees which make up the process of taking an interesting idea into fruition; to the point where it is usable and marketable:
First of all you have the labour costs of the consultant, which depending upon the demands for their services, could range anywhere from £50 an hour all the way up to £300.
Secondly, you have the additional services of 3D printing, which will give you a solid idea of what the product will look like at the end, and is essential to product design.
You need to be prepared to spend at least £500 for a very simple product design, but for products which are truly worth getting right, expect to pay at least £10,000.