Don't charge - release it as Free/Open software.

Then provide way for people to donate whatever they like, based on how useful it is to them. *(Unfortunately, I don't actually know how effective this is.)*

If this is a core product for your company, you can still do the above, but also a commercial license and support contract, and maybe sponsored feature development too. 
*(This model is used at big software companies such as [JBoss](http://www.jboss.com), [MySQL](http://www.mysql.com), but smaller companies such as [BlueRiver](http://www.blueriver.com) or [Railo Technologies](http://www.railo.com) also do this successfully.)*