I like the original astronaut space pen (the AG7, made of chrome-plated brass). Can usually be found on Amazon around the $50 mark

The Parker Jotter in stainless steel (commonly called the "Flighter" model in the UK, and a notable prop in at least one of the Bond movies—GoldenEye) is also a good choice for much less. 

The Caran d'Ache 849 is probably my favorite ballpoint pen and comes in a variety of fun colors in the $20-50 range.

I don't know how much of it is digital now, but pilots used to do quite a bit of pre-flight paperwork and even today it's common to see them with a pen or two in their pockets.