As has been noted elsewhere, the upcoming clay sale at Trinity runs from January 19 through Feb 5. Traditionally, this does not include a Saturday, as they get the Saturday off for the holiday, and they don’t work some other Saturday.
Pricing is the 1000 lb pricing for most all the clay. It usually excludes the expensive non-Trinity clays, like the Grolleg porcelain. It’s not quite 50% off the regular price, but it’s close.
Trinity runs 2 sales a year, which are set to coincide with the spring and fall semesters. The next sale after this one will be from late August to early September.