Broadside used to do them aswell before they shut down, I think someone else bought all of the cameras when they shut down and are now hiring them.
Andrew Purcell (Action Cam) was renting them for a while aswell, not sure if he is still at it though.
JP Ruth of Ruth Motorsport is also able to source some for hire..............
Graham Scallan that rallies the Cuisine de France mk2 has bought the Rally Cam franchise that used to be run through Broadside. Saw one of the dvd's lately, quality is top notch, put together very well and as far as I know prices are very reasonable.