Parker Jotters are great and cheap. There's a reason they're still the default 'better-than-Bic' after so many years.
The Caran d'ache colour series are lovely too, and being metal, have a more premium feel.
There's also the Fisher Space Pen - I love the history and though they're expensive, I tend to carry one in my pocket.
Long out of production (and not very ergonomic) but my all-time favourite ballpoint is the Aurora Thesi. I keep one on my desk.
