What program can print source code well on OS X?

Solution 1:

You will find a nice answer over at sister site superuser. It involves a terminal program called enscript which comes with lot's of options and I know at least of one support file for extending its capabilities to print Ruby code.

EDIT:

I just noticed the "clipboard" part of the question. The clipboard content can be accessed from the command line and fed to enscript using pbpaste as mentioned in Matteo answer.

Solution 2:

If you don't want to use the terminal for this task and want a mac 'application' you should look at 'Text Wrangler' by Bare Bones Software. It is freeware, which fits your 'low price' request ;)

I use it to print out smaller runs of text, and use it specifically for the line number feature.