Well, the ideas meant to be sold aren't related to a business of mine.

They are just ideas about things that don't currently exist or improvements of existing products.

What I want to sell is the idea as it is.
The workability evaluation should be done by the buyer of the idea.
Sounds logical because he is the one who's suposed to be an expert within his field.

The thing would be to get paid only if the idea is viable in the end.

And I'm not sure I would want to wast my time and money with lawsuits in case someone breaks an NDA.

For anyone who has the technical means, any idea can be easily copied.