Give them gift ideas! It's all about IDEAS!! Maybe decorate with a little tinsel and garland and a small tree. Dress in holiday attire. VIP has those cute little santa hats...I bought one last year!
Have you seen the Gift Ideas Cards I made up in the docs?
Gift tags for gift sayings...I use those and group things together. I write the products on the back and a aproximate total gift idea price. I've had really great comments about them. I even had a lady call me and ask me to set up a booth at a childcare conference earlier this fall because she loved my creative way of doing things....

If the fair doesn't have music going already, you could play some very soft Christmas music in the background. Make it seem nice and cozy...just like the holidays!