This is an attempt to be legal here.
Second hand is probably your only legit choice now, allegedly Games Planet have it but it doesn't seem to be listed, at least I can't find it.
The IP: Get a comfy chair as this is a bit long.
"IP: This was developed by Warthog Studios. Warthog was sold to Gizmondo, along with the IP for RBR. The game was released on the Gizmondo by the developer "Gizmondo Studios Manchester". Gizmondo went out of business, and Carl Freer, founder of Gizmondo, claimed to have purchased Gizmondo's IP assets from the liquidation of the company. I assume the owner of the IP is Carl Freer if he is telling the truth (if you know anything about Carl Freer and his Gizmodo partner Mikael Ljungman, than you know this is a BIG if).
Publishing rights: SCI Games owned the publishing rights, and was the publisher for both the PC release from Warthog Studios and the Gizmondo release from Gizmondo Studios Manchester. SCI Bought Edios and released all games as Edios from that point, then Square-Enix bought Edios (SCI). The terms of this publishing deal is unknown, but I would assume the publishing rights probably have expired and there is no holder of publisher rights for RBR at this time.
Car / personality rights: No one is privvy to these deals either, and I really don't know how they normally work. My assumption is that the cars were licened to be used in the game, and if there were to be a new publisher, they could publish the original game without having to relicense."
So, no one seems to know who actually owns it or if the 'Richard Burns' and the cars IP rights are still valid.
Still here ?
Try reading this,
https://pretendracecars.net/2016/12/11/still-the-king-richard-burns-rally-2016/
This is Richard Burns Rally 2016, it has a set of inbuilt mods and plays really well.
Try it and see what you think.
I'd posted this as a Xmas pressy a few posts ago on this thread.
EDIT: The subreddit has some great conversations on mods, getting it running etc.
https://www.reddit.com/r/simracing/comments/5i3btq/richard_burns_rally_2016_updated_and_free/