Of the times you have proposed NDA in exchange for a fee, what were the outcomes? They pay? They walk? They waive the NDA?
NDA's and Non-Competes both change my requirements.
Without them my rates are $150/hr with 40 hours pre-paid upfront to discuss the project. When we move forward those 40 hours are credited to them.
If non-compete/NDA is involved, my rate goes to $300/hr with non-refundable $10,000 deposit that does not translate to credits.