If you happen to be looking for the fountain pen from Kingsman: The Secret Service used as a weapon, then you can find it at this website, Mr. Porter.
Valentine, Sam Jackson’s character, uses a gold fountain pen when making a list a little over halfway through the film. It’s the only place where you see real writing with a pen, but I’m not sure what pen it is. All the reviews are focusing on the Conway, as it’s used as a weapon and is fairly famous.
If you’re interested in fountain pens but are – like Eggsy – lacking a silver-spoon suppository, please know that there are dozens upon dozens of options out there of fountain pens that are completely affordable. Otherwise, how the heck would I be able to buy any?!
(And, yeah, I totally went back and saw the movie again. It was still fun a second time, though I think I was better able to pick out the stunt-double parts, I wasn’t perfectly sure. It remained awesome. And that three layer ending still worked, too. Loved it. Just remember… don’t take it seriously… just go for the crazy.)