This one is for the graphic designers in the crowd, as opposed to the type designers (who would have a totally different answer, I think).
How much money should an independent graphic designer, working alone or in a small group (two or three), budget each year for font purchases? Five percent? For a solo act doing $100,000 a year gross, that is $5000. That should be enough to keep the library current.
What do others think or do?