A surprise for your customers? They'll hate that!

Why people choose...
Uber? Because they feel confident. No surprise, you know the price In advance and how it works. 
Audi cars? The same. No surprise, it's German quality.
Zappos? The same. No surprise, you know they propose an amazing service and have fair prices.
H&M? The same. No surprise, it's cheap stylish clothes.
Chipotle? The same. No surprise, it's Tex Mex food made by humans with good ingredients.
Qatar Airways? The same. No surprise, it's Gulf county airways have great planes and good films.
Aeroflot? The same. No surprise, they are safe enough and the cheapest.
Your favorite bakery? The same, you know it's good quality for price.

People hate surprise, hate risks, hate uncertainty. Give them certainty, and they'll never go elsewhere.