Lex,
The thing you have to remember here is that you are talking to a bunch of domain resellers, even if this was a domain worth £25k to anyone (Which it's not), let's say for example you had cyprus.com, now for this name it is possible that it is worth £25k to an *END USER*, not a *DOMAIN RESELLER* (Unless it has high PPC potential).
Domain resellers buy at a lot less than end user prices as they are keeping the domain to market to certain end users for a higher price, or to sit on and wait for an offer on Sedo etc.
You cannot expect to come onto this or any forum full of domain resellers and expect to command such a high price, we see 3char (LLL.co.uk's) going for 3 figure sums here (Which will sell all day and are easy to target end users with), you come on here and ask a 5 figure sum for something that quite frankly isn't as worth much as a domain I sold on here earlier today for a few £'s
You need to decide who you want to target, as you will never sell anything asking very high end user prices to domain resellers.
If you want the big sales, you need to try and market the domain to potential end users, then you can demand the higher prices (But you have to be prepared to put a lot of hard work in).