I get a 12.5Kg mix from equinecaninefeline.com
This mix has no added colorants or preservatives. It contains Barley, Whole Maize, Small Dark Striped Sunflower Seeds, Monkey Nuts, Paleskin Peanuts, Clipped Oats, Locust Beans and Wheat. Suitable for use as a complete feedstuff. This particular food is recommended by chipmunkrescue.co.uk as being very suitable for chipmunks.
And my little guys love it

.