Lovers of the Pilot G2 series of pens, take note: the so-called G2 ‘Pro’ version of the writing implement is only very marginally superior to the disposable model. Both are made of similar plastic, and the clicking system for retraction actually feels a bit cheaper on the $5 ‘Pro’ pen than on the $1 disposable pen. Since the ordinary version takes refills just as well as the more expensive one, there is no real reason to make the switch. In fact, the cheaper pen actually comes apart more elegantly to be resupplied with ink.
If you want a genuine step up, using the same ink cartridge system, hunt around for the metal bodied, $12 G2 Limited.
On a side note, it strikes me as odd that, while I have dramatically more expensive pens than the G2, I rarely feel comfortable carrying them around. As such, they languish in boxes in my apartment while everything from letters to to-do items on 3.5″ cards emerge from the tip of Pilot’s low-cost devices.