I am a serial inventor and have been producing new products since the early1990's . I have had many patents to my name, have worked for the UK Government as their innovation advisor and for the past 15 years I have been Chairman of the Judging panel for the World Innovation Awards.
Your product sounds interesting and if you believe that it is unique, innovative AND that consumers will want it then there are several things that you should do, in my opinion.
NDA's are useless in terms of what protection they may be able to offer to you HOWEVER, I always believe that you should get them signed by ANYONE that you share your idea with. Why? because they form a part of your IP inventory and if later on you are seeking any kind of funding it will be great to be able to tell potential investors that you have been diligent enough to insist upon NDAs because is will be testament to your management skills and your eye for detail. They are also CRUCIAL if anybody decides that they wish to challenge your patent one day on grounds of it having been in the public domain prior to you priority date.
Patents are very cheap, initially, and are an excellent form of protection. Again, as a balance sheet item they are also hugely valuable; whether you are seeking investment or an eventual exit route. For the first year, you will have worldwide protection at minimal cost. Later on, if you decide to go for individual territories then you can backdate your patent applications to your priority date. This must be done , however, within a year of your priority date.
Patents, of course, don't only protect you with regard to manufacturing rights, they also protect sales. So, if someone is breaking your patent in terms of manufacture, you can slap an injunction onto anyone trying to import/distribute/retail your product in a protected territory.
With regard to prototypes, I would strongly advise that you DO consider China. There are absolutely incredible prototyping companies and services available there and they generally produce immensely fine products at a fraction of the cost of western companies. And generally in a far more timely manner too! The thing is that you must be very wary about who you approach and also make sure that you have great refences on them. I would always suggest a face to face meeting or the use of a local ex-pat to guide you in this process. It would be foolhardy to approach manufacturers or prototype makers by email or phone other than to establish initial communications with a view to an eventual face-to-face meeting.
I spend about half of my year in China and know plenty of design, prototyping and production management firms (generally run by ex-pats) where security is tantamount and quality and service is second to none. Conversely, I have had many prototypes made in the west and although quality has been fairly good, these have tended to be slow and overpriced affairs. My Chinese prototypes, on the other hand, have always been of the most astonishing quality, regardless of the complexity of the product.
Finally, in my experience, one rarely has problems with copy-cat/rip-off manufacturers until a product is hugely successful. Counterfeiters are not in the business of developing new markets, that is far too risky for them. They prefer to steal their way into established markets where demand is high.
I am sure that I can assist you and I am happy to have a follow up call with you if you wish to get any further information or contacts from me.