I have a great idea for a phone accessory that has never been done before. I don't have thousands of dollars to patent the idea, so my idea was to try and find a Chinese manufacturer to produce my accessory. Would I need a prototype first? Would a NDA help in protecting my idea until I can afford a patent?
I want to begin by assuring you I don't want to rain on your parade. Now...
Ideas are a dime a dozen.
Execution is what is critical, and hardly anyone does execution well.
NDAs are nice but they won't protect your idea from being ripped off in the medium term at the latest, if it's a winner.
Your best protection is that execution thing...people sure like to talk, but they don't like to Do.
Do NOT have your prototype made in China. It will take months in shipping back and forth, misunderstandings, finding the right manufacturer, and other difficulties. Do not embroil yourself in that mess.
Absolutely you should get a prototype made first. Will it cost you 10-100X what the final version will cost? Of course. Do you need something to show investors, suppliers, channel partners, retail outlets? Yes.
All a patent does is protect your idea for awhile from being duplicated in the exact way you are executing it.
I can't go make a sticky-note that uses a strip of lightweight glue to hold the paper onto something. 3M has that patent. But I could find another method for holding the paper on, and that would be fine.
Worrying about protecting your idea is kind of a waste of time. You should do what you can afford and what makes sense in terms of your time invested to accomplish a level of protection, but don't let this be all-consuming. It's just not worth it.
Get out there and make your product and find paths to market. That's what will really pay off. Someone WILL copy your product sooner or later if it's a money-maker. That's why developing great branding is so important: keep the knock-offs in the knock-off category in your buyer's brain, and you as the top quality original.