This is another one that I regularly use. Not only do they do nuts in the threads in post #1, they also do a wide range of materials - several grades of stainless, brass, aluminium etc.
I've just bought five 0-80 UNF in A2 stainless for a quid. Shipping and VAT was the majority of the £4.76 total. But I got them in two days.
https://www.accu.co.uk/en/
Craig