You do not want sodium nitrate, you need sodium nitrite. Sodium nitrite is the one that works as has been documented here and on many medical journals.
I suspect (please correct me if i'm wrong) you may not want to order it online because you are afraid your family could discover it in the mail. I recently ordered SN from the popular retailer named after a long south american river. This company offers an option to ship it to a delivery box where you can pick up the SN.
By google searching for if its sold at home depot i could not find it but it looks like WMT carries it.