Teach Soap

I have been thinking of offering some type of reward to increase repeat customers, and could use your suggestions.
What type of reward should I offer? Do you prefer using the "old fashioned" card that you stamp or punch, or do you prefer something like Belly or what Square offers (both cost $25-30 or so per month).
I make soaps, lotions, bath bombs, etc.
I would like to offer something my customers will like but something that will not hurt my earnings too much.
Any ideas?
Thank you, thank you, thank you!

I send a business card size discount that my customers can use on their next order with a special code.

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Irena
Closed minds are like faulty parachutes; they refuse to open.