In terms of domains, prices vary hugely depending on the buyer. Someone might love a domain www.jkosdfhjkdshf.com and feel its worth $#*$!x amount while others wouldn't even pay the registration fee.
Often is very much worth putting a site on there and even pushing a few uniques through via another site. A domain with content and traffic (no matter how small) is worth more than one without.
Same goes for PR... alot of people will still buy a site based mainly on a good PR, while others (like me) feel this isnt as important anymore as it once was.
In terms of the transaction... its normally a case of you receiving the money before pushing the domain, it would be unwise to push it before the money comes though - no matter how good the buyers reputation. Some people do it simply by PayPal while others will only use Escrow.
.co.uk do sell well, but not aswell (generally) as the 'premium' extensions (.com, .net, .org) but they can still sell well.
Good places to sell are webmaster forums, Afternic, Sedo, Great Domains, etc. <snip>
- Goodluck in your sales :)
[edited by: Webwork at 2:19 pm (utc) on Sep. 10, 2005]
[edit reason] Tidying up [/edit]