Doing this purely through numbers...
1. 3DTV.co.uk sold for £15,000 from memory
2. Plural gets roughly 10% of the above singular searches (so if it was a .co.uk = £1,500)
3. At a very broad level, .org.uk is roughly 10% of .co.uk price
= £150 for 3DTV.org.uk
May well be able to get a better £xxx offer from someone on here but I can't see it going into four figures. Also, it's technology which hasn't really taken off yet which could be either good or bad for you. Personally, I can't see it become mainstream.