Valuing a Domain

It's renewal time for opus.cx, the domain we use for our content management system and it's going to cost us about £41 for one year to renew, which is a bit steep. So I idly wondered what the domain was worth. How to find out? Well there's lots of sites that claim to be able to value a domain so I tried a few, all found on the first page of a Google search for "value a domain".

Here's the results:

So that's helpful then ...

As someone remarked on a forum I found:

IMO there is no such thing as a good [domain value calculator] - they are all useless. A domain is only worth as much as someone is willing to pay for it.