Try Jungs or Gurneys. They have them in lots of 25 or so.

I was looking for ages and finally found some pint sized wood berry boxes (they have quart size ones too) with no big minimum orders at Garden Time Online.

I sell blueberries and raspberries at our local farmers market. I never ordered berry boxes from Gurneys, they only had the quart size, I needed the pints.

Here is a link that might be useful: Wood Berry Boxes

I couldn't afford the berry boxes just starting out with my blueberries so I went to the store and bought paper lunch bags. I measure about a pound worth in each, roll the tops down so people can see the berries and they can always unroll the tops for easier carrying when they buy them. You can also double the amount of berries using the same bag.

You can try Greenfield Basket Factory. I just got their new catalog and they have cheap berry baskets.

Here is a link that might be useful: Basket info