Both these makers have been recommended in these forums:
Old German Clay Pipes of first-class quality at Cigarworld.de ✔︎ Largest assortment in Europe ✔︎ Shipping within 24 hours!
www.cigarworld.de
Studio Devona Clay Pipes for Sale. Previously Dawnmist Studio Clay Pipes, and now since 2025 Studio Devona Clay Pipes. This is the main sale page for clay tobacco pipes made in Devonshire UK. New Clay Pipes for Sale.
studiodevona.co.uk
Have seen nothing Stateside - sorry (but I haven't looked very hard - I'm a Brit in the UK).
I've always smoked whatever clays I can get new, and have noticed no difference in quality (I suspect those have all been British). I just put in an order from Devonia for a couple more this evening.
To my mind, clay rivals Meerschaum or cob for a clean, cool smoke in a pipe that can't be ghosted. Its neutrality, unlike briar, means it's not biased in flavour by whatever you've smoked in it before. They are perfect for trying out a new blend - and you don't need to rotate or dedicate.
As OzPiper said, they can be fragile, so knock your clay out gently and find something to carry it in - I wrap mine in a cloth to carry in my coat pocket, but some prefer a pipe case.
They burn hot, so avoid touching the bowl. I hold the shank between two fingers, as one would a cigar or cigarette.
Many clays - most over here - come with a protective varnish on the mouthpiece, which prevents your lips sticking to the clay and possibly skinning them, as can happen with an untipped cigarette; the two manufacturers listed above do not varnish their mouthpieces so I'd advise, if you do buy from them, that you paint the last inch with a clear nail varnish - either that, or get one with an acrylic stem.