How about contacting local businesses about donating small items or gift certificates. Often times, the smaller businesses are willing to do this because it is advertisement for their business, especially if it's a gift certificate, because then your Employee of the Month is likely to come to them, and then they may discover that they really like that business and come back.
Some ideas of local businesses to ask:
Drycleaner
Salon (hair styling/manicure/pedicure)
Car wash
Small shops (these are often found in groupings like a flea market...they are small shops just starting often, but some have some really great stuff, from clothes to jewelry to religious products)
It all depends on what's in your area. It's more fun to have a gift basket type of thing...you could add simple things like candles ($1 each at the dollar store), bath beads, a 'Good job' card, and mamny other things...use your creativity!
This takes more work than a simple gift certificate, but people appreciate it more because it shows you really care enough to take the time to coordinate this Employee of the Month basket. Dress it up in a little basket (easily found at the dollar store or a thrift store) with ribbons and maybe even a good job baloloon if you want (again, a dollar at the dollar store), and you have something that shows everyon THIS is the Employee of the Month!
Then take a picture of them and hang it up somewhere prominent, such as in the main waiting room or the main office.
If you don't have time to coordinate this yourself, ask for a volunteer for it. Make them the EoM coordinator officially and let them go at it. Some people are really good at being creative and would love the chance to show that.
Hope that helped!