You can also knock some more off or even get it free by using the demo version if you create a filter that reaches a certain popularity. You need 3 popular rated filters to get it free but each one you get gets you a percentage off. In addition Beta is out for version 4 and you can also win a copy I believe for discovering unreported bugs - though it's been in beta a few weeks so bugs are disappearing.

Version for allows you to group a series of controls -useful for big filters that might have dozens of components and to reuse certain segments i other filters, it has some sort of looping or recursive compnent and lots of other features that really power it up to a whole new level.

Here's the beta page https://www.filterforge.com/download/beta4/