The simple answer is...quite a lot. New prototyping and production methods have lowered many costs, but product development is still an expensive process, particularly when testing and marketing are taken into consideration.
Design and development costs
Like all product development costs, design expenditure will depend on complexity and the amount of time required. A simple, small product - like a coat hanger or clothes peg - may cost a few thousand pounds to develop, including the CAD data for production. A complex product like an item of consumer electronics may cost several tens of thousands of pounds.
Prototyping and testing
Prototyping costs have come down with the wide range of 3D printing and CNC options available, but expense will also depend on size and complexity. Small, simple products will cost a few hundred pounds, complex ones many thousands.
Testing costs will depend more on the product function than its size or complexity. Many products will need little or no testing, but safety-critical devices may cost many thousands of pounds to test and re-test as needed. Do not, whatever you do, attempt to save money on testing!
Tooling and production
A small, simple injection mould tool will cost a few thousand pounds, whilst a large complex one will be many tens of thousands of pounds. Tooling for other plastic processes, like vacuum forming, that do not involve high pressures, will cost considerably less.
The tooling set up costs for machined or fabricated parts often runs to only a few hundred pounds, but the individual parts are more expensive than a moulded equivalent. This is why it is vital to consider production volume early in the design process - there is an important link between the quantity you make, the part cost and the tooling investment. Arrange a meeting with us if you would like to discuss these issues in more detail.
Marketing and promotion
The use of social media to promote products has cut marketing costs dramatically - particularly if it is well targeted and focussed on real customer need, but a good programme will cost thousands of pounds. The cost of a well-produced video will also cost several thousand pounds, and a professionally produced website will require a similar investment. However, apps like Wix, Squarespace and Wordpress allow you to develop your own website for a fraction of that investment if you are prepared to spend some time and effort.
Advertising in conventional media remains expensive, but is worth considering, particularly for specific markets catered for by specialist magazines. A half page ad in a well-known technology magazine, for example, will cost you £1,000.00 per advert.
The most important thing to recognise that is that the old addage is completely wrong - building a better mousetrap will not result in the world beating a path to your door. You need to be prepared to spend tens of thousands of pounds to let your market know you are there and what your product can do for them.
Adding it all up
Product development is an expensive process. If you are planning on designing, developing, prototyping, testing, tooling and promoting a mass produced new product - even a fairly simple one - you need to plan for a six-figure budget. If you are planning to make something on a smaller - more craft based - scale, the sums required will be dramatically lower - maybe in the high thousands.