We just received word that the Indigo renderer will no longer be free (there'll still be a trial version with a small-sized render and a watermark). For now, the news has only been announced to their beta users, but a full announcement should appear shortly. The best of luck to you guys!
From the announcement on their forum:
This is also our early announcement to the beta users - that Indigo is going commercial. We will still have a free version which is fully featured, but limited to renders of 800 x 600 pixels and with a small 'indigo renderer watermark' in the lower right.
Commercial licenses for Indigo will cost 595€ for a full version, or 195€ for a node license. To say thanks to all the early adopters of Indigo, we are offering full version licences for 295€.