Once you have invested in an employee's training, it is always in your best interest to retain an employee rather than have to replace one.
Along with paying them a decent livable wage, there are a few little or no cost perks that you can offer that will keep most employees happy.
I don't know about you, but most people love free food and will especially look forward to a day when they do not have to pack a lunch.
Another perk to consider offering around holidays is to give your employees a gift certificate for a free turkey or ham for Thanksgiving or Christmas. This also can be done as a trade with a local supermarket.
A third and low cost perk to offer employees to give them misprinted shirts. If giving away the shirts will not present a conflict with customers, let your employees pick over the misprints. Having to buy clothes cost money and your employees will appreciate getting free clothing for themselves and their families.
The time and investment you made in training your employees is certainly worth the small amount that you will spend in providing them with these low cost, high value perks.