Based on your request for the best estimate, I recommend consulting with one of our Clay experts. We have partners with various price ranges ($2K-$15K) and specialties who can provide accurate estimates for your specific needs.
Alternatively, you can use our credits calculator to estimate usage costs if you're looking for pricing on our data services: https://www.clay.com/credits-calculator
For a more detailed estimate, please share more specifics about your request.