I agree, I would have paid twice that at least for pleasure.
Had a thought with your domain. I wouldn't let it go too cheap. Although we should always take a good honest buyer as they don't come round too often, I feel monkey.co.uk is really good. I think to the right enduser it could be like monster.co.uk
What I mean is it could be used for something with no relevance to obviously monkeys, but it is so memorable. Good luck, I think you can hold out for quite a big pay day!