Last year I wrote about the Google Patent application (from March 2005) on aged domains, this is a significant issue when it comes to optimisation for search engines. The article explained how they were going to filter against new domains on competitive search terms. Its argument is that "how can a new domain be authoritative?"
The advice at the time was to either buy old domains that have, for whatever reason become redundant, or otherwise buy the domains you might want in the future, lay them down and let them mature.
But what if your primary domain name has been around for some time, and you realise you need to launch another associated site but didn't have the foresight to buy it years ago.
You have a couple of options, you could just buy a brand new domain, but that will limit your success in the search engines for a couple of years, so the obvious answer is to buy an already aged or expired domain.
When buying a domain from a seller, you will often find they have unrealistic expectations as to its worth. Brokers are often better but even these are littered with over priced domains. If you are on a budget, sometimes the route to take is to snap up domains that are either expired, expiring or due to expire. This however is not the easiest of processes to do yourself.
If you have found a domain, and it looks like it is about to expire, don't be fooled into thinking you can "snatch" it just because it expires on a given date. Realistically domains don't expire on the date signified by WhoIs. The domain will go into a period of grace for 40 days, during which period, the owner can renew at the standard fee. After this period the domain's status changes to "redemption period". The WhoIs information will start to record, 'no owner attributed'. Should the owner want to re-register the domain, it will now cost an additional fee to recover it.
Finally, after about 70 days the domain moves to the "deletion"period. At the end of this period the name will drop from the ICANN database, which makes it publicly available for registration by another owner.
You could try to snatch the domain yourself, although this is unlikely to be as effective as using one of the many domain snatching firms. That said it is well worth buying aged domains instead of new ones, and if you really want to stay out of trouble once you own them - keep an eye on them, don't let them lapse.