There are two markets for air dry clay in the UK and they are priced very differently. Craft retailers sell small packets, which is right for one project. Pottery suppliers sell the same category by the bag beside their fired bodies, which is what anyone making repeatedly, or equipping a class, should be buying.
The packet market and the bag market
A packet from a craft shop is convenient, available on a high street and expensive per kilogram. A bag from a pottery supplier is heavier to get home, needs storing properly and costs a fraction as much for the same weight. The gap is wide enough that a school or a regular maker recovers the difference in a term. Neither is wrong; they answer different questions.
Who stocks it
The suppliers this site prices carry air drying bodies alongside their fired ranges, which is worth knowing because most people looking for air dry clay never think to look at a pottery supplier at all. Bluematchbox lists an air dry range with grey and red bodies as well as white; the others carry it among their general clay listings.
What to check before ordering
Bag weight, because these vary and a price is meaningless without it. Whether the body is genuinely clay with a binder or a clay-free modelling compound, which changes what it can do. And the delivery charge, which on any clay order is a real part of the cost: a bag is heavy, carriage is priced by weight, and two bags usually ship for little more than one.
Storing a bag once it is open
An opened bag dries out and a dried-out bag is a nuisance to recover. Keep the clay double wrapped in plastic with the air pressed out, in a cool place off a concrete floor. Take out what you need and reseal immediately. Clay stored properly keeps indefinitely and in fact improves with age, so buying by the bag carries no penalty other than finding somewhere to put it.
Questions people ask about air dry clay
Where can I buy air dry clay in the UK?
Craft retailers sell it in packets and pottery suppliers sell it by the bag. The bag route is substantially cheaper per kilogram.
How much cheaper is buying by the bag?
Enough that a class or a regular maker recovers the difference quickly. Compare on price per kilogram, and add carriage, which is significant on a heavy order.
Does air dry clay go off?
No. Kept sealed and cool it lasts indefinitely. Only drying out is a problem, and dried clay can be soaked and reworked.