There are lots of benefits to buying an aged domain, which is an ideal strategy if you are building a new website. The immediate benefit comes from the reputation which, may have been previously established, where the older is better.
The primary reason for the preference for an aged domain, is that traffic and reputation may have already been established. However caution is required to determine whether any effort has been put into developing the site, if it exists, or is simply a domain name.
Aged domains are available at various prices, which are determined by the intrinsic value. If you are developing a new site, an aged domain can put you miles ahead of the competition, where the need to develop inbound links and site traffic is already completed, but the difficulty lies in determining how to make efficient use of the reputation, but even more important, is determination of the value of the links.
There are several sites where you may buy established domains in your category, but before doing so, an examination of the link profile may be necessary. Determine if the inbound links are appropriate and able to send the right type of visitors as quality becomes even more important than quantity.
If all is in order, to make use of the traffic, the next objective would be to direct the traffic from the old domain to your new domain. This should be done discreetly as search engines really do not like redirects, and generally not much value is passed on redirects.
Do not expect that your site will receive higher ranking in search engines from redirects, as there are several other factors that come into play. Do not expect to receive from credit from domains that may have already expired.
Where real benefit from an aged domain can be derived, is where a domain is transferred, or if a website is bought or sold. If you intend to operate the site in the same manner, despite the new registration, it is more than likely that credit for the existing link profile should continue.
Another option to make use of an aged domain, requires a bit more effort, but can have a positive impact onsite performance. The old domain can be set as a sub or microsite, which can then be linked to your main site. In that way much of the value with the established microsite can be passed to your main site, without affecting site reputation, but the downside, is that a bit more effort is now required to maintain two websites.
The third option is to completely rebuild a site on the old domain, and this is not always as daunting as it sounds, but you have the ready benefit of making use of an already established reputation.