Now, I have checked this site out before, and though that they were quite pricey. However, when you're getting half off, it's not bad!
Since you have to use the whole voucher at once, let's see the best way to do that...
They've got a mixed box for $31.50, so you'd pay $0.50 plus the $15 for the voucher.
Here's what's in it: 4 Cara Cara oranges 3 Pink Lady apples, 2 Eureka lemons, 1.5 lb Garnet Yams, 1 lb. Murcott oranges, 1 bunch spinach, 1 ct. leaf lettuce, 1 bunch collard greens, 1 bunch broccoli, 1 head celery, 1/2 lb. strawberries.
Not bad for $15.50 delivered straight to your door! Plus, you're buying from and supporting a local farm, so you can feel good about yourself. :)