Reddit reviews Zziggysgal Dried French Lavender - Select grade, Certified Kosher

I buy it at my local farmer's market and grow it myself. If you don't have access to either of those means locally, then here it is on amazon. I've never purchased it offline, so cannot testify to its quality.

Amazon has some here for $14 a pound. I'm not sure where you'd buy it from a brick-and-mortar store, however. I'd check out health food stores, organic food stores, flower nurseries, or botanical gardens.