Just found the 18CD Rory Gallagher at the BBC box set, released last year.
Insanely expensive from Amazon (suspiciously much cheaper on eBay) and for completists only.
The veritable Grateful Dead archive of Rory Gallagher performances.
The Amazon price is just an algorithm price - not a realistic one - I imagine. The prices on eBay are not suspicious, I don't think (reasonably close to Discogs prices etc.), although personally, like most big CD boxes there will be some dodgy copies around from Asia I imagine.