If you are desperate about getting rid of them, you can send them to a bot such as "Dota 2 Dispenser" (http://steamcommunity.com/id/dota2bot?l=english) who will take them and send them to people that request a copy. I have used the one mentioned above and it was quick and easy, and they are no longer filling my entire inventory! 
Thanks, I'd never seen that, I sent a few there as it was a nice easy off load, I've kept a few as only 3 people asked, although I did post it rather late last night.
And thanks b!z, I'm not really after any money for them as I like giving things away when I can so was looking to offload them to anyone who wants one or knows of someone who might need one.
Also just throwing this out there, does anyone play Tribes by any chance who wouldn't mind joining up later for a couple of rounds?