I get mine from From Nature With Love -
1 pound for 6.25 (roughly 450 grams).
It's totally gritfree, amazingly fresh, color releases in under an hour, and it slides out of my hair. Everytime I've used something different - I've regretted it. And maybe my Indian stores are just slow on the rotation, but all the on the shelf henna I've seen in this area is either old, gritty, or both.
I henna once a month, and a pound lasts me for a good six months or more....