A few months ago we purchased American DJ's MY DMX 2.0 to run some new lighting in our youth space. Shopping for a good lighting controller solution has always been a pain for me. There just seems to be so few options and they are all so dang expensive. I was really excited to see the power of MY DMX shortly after we began using it.
In the box you receive the usb to dmx interface. You can download the software here. The usb interface functions as a key to unlocking the software. We have it installed on two computers in our church, one in our main sanctuary and one in our youth space. Depending on whether it's Sunday morning or Wednesday night, I will move to the usb interface to the appropriate space and our light control is up an running in seconds.
There are some limitations to this software, but none that are too difficult to work around. The basic idea is you will want to setup scenes for all the different aspects of your worship service. We use Ableton Live to then cue the appropriate scenes at the appropriate time. Even without Ableton, MY DMX 2.0 is still a great solution for affordable light control.