Experiments are conducted in Predictably Irrational by Dan Ariely.
Passers-by could choose between two different chocolates:
A Lindt chocolate for only $0.26
One cent gets you a Hershey’s Kiss.
There was a 40% uptake in truffle sales.
Forty percent of people fell for the Kiss.
The scientists then made a dime adjustment to the prices of both chocolates:
The price of a truffle had increased to $0.25.
This liberated the Kiss.
The results showed that despite the small price difference, 90% of buyers opted for the free Kiss chocolate.
You should consider giving away free samples of your product if you want people to keep coming back for more.