I have never found then in the hardware stores as stock items in the USA. I'm sure somewhere they sell they as stock items but not that I have found. I had to purchase whole sale and buy in big bulk to get them to sell to me. Then they don't make the drip feeders they only sell the single parts and the feeder is hand made.

I assume you can get them online somewhere but the ones I could find were attached to a thin wall flex tube and not a ridged 1/4" feed line that does not bend from the lights.

They are fair priced too for all the work in them.