"That's the very reason you should buy."
Examples
Customer: "Your price is too high"Salesperson: that's the very reason you should buy. The more the cost, the better the quality"
Customer:"The quality is cheep"
Salesperson: That's the very reason you should buy. You can throw it within 6 months and go for a new one."
Customer:"I don't like Black color"
Salesperson: That's the very reason you should buy. You've to get use this fabulous color as Black will hide dust and dirt and you'll fall love with black from now"
Customer:"Your brand seem to be new in the market"
Salesperson: That's the very reason you should buy. New brand, new taste.