I can still remember (as it was only 10 years back) when in the UK the only people watching out for Black Friday deals were Apple fanbois as it was the only day in the year when Apple would discount some of their range, the discounts being global, and some very good bargains to be had. I think it was only really with Amazon joining in and pushing the event world wide that the fuss spread over to this side of the pond. Since then it has waned but there can still be some good deals to be found.
From a fountain pen basis here are the ones I’m aware of in the UK. I’ve listed them in alphabetical order for the retailer and have only included those listed on their websites or mail pushes. Please note this is also based on the list of retailers I have in my browser and are actually advertised as Black Friday deals, not just their regular offerings. Any I have missed, please let me know and I will add.