If you are aware of any asian grocery store, specifically Indian you may find it.

Dill seed is almost always available in the bulk spice section of your grocery store, they are also available with the regular jarred spices, but are more expensive that way. Sometimes they're with the pickling spices in the spice section (like there's a nice rack of pretty spices all the alphabetical order, then in the lower shelves there are big boxes of seasoning salt and smoky rubs and salt substitute, it might be in that mush of things in a "pickling spices" sort of section).

I get my dill seed at our local health food store.

Penzey's. http://www.penzeys.com/cgi-bin/penzeys/p-penzeysdillseed.html