What he said... I usually pick up mine at Home Depot. I like the Deft clear wood finish. It should also be available at Woodcraft and such. You can try this link.
You aren't going to find a can specifically named "lacquer". You will need to find the brand names and look for it that way. As mentioned, Deft is one brand that is pretty much carries everywhere. They even have a new water based finish, although I'm not sure how that will work on a pen.