What about option #4 - Redirect your existing domain to the old domain? I bought an old domain that is 100% relevant to my current domain but currently has with very little content. It did have more content fours years ago. The old domain is 13 years old, pr=3, while my current is 7 months old pr=1 and a decent amount of content. The old domain I purchased was not expired though and I do not know if this makes a difference. What are the pros and cons of option #4? Am I correct to think that option #1 would result in no benefit from the old domain's age value and if so why is it not listed as a con, a MAJOR one. Its hard to believe that a 301 using option 1 would give my existing domain 13 years credit but I'll take it if it does.

Hi Kulwant, these are great tips as usual. I particularly like the way to tell us to check the google pagerank in case the domain has been banned – that could lower the usefulness of the domain quite a bit. One thing though, don’t you think that buying domains is sometimes immoral? Like sometimes you accidentally buy a domain of somebody elses website who forgot to renew.

Page authority ranking criteria are similar to domain authority. It’s ranked on a scale of 1 to 100. Page Authority measures the predictive ranking of a web page. The page authority of a website can change depending on various metrics. Search engines examine the relevance and authority of a page based on its contents and external links. If a webpage has links to higher authority sites and has keywords in it, its authority ranking will increase.
GoDaddy Auctions is a marketplace where GoDaddy lists domains that have expired and are in the renewal grace period. Apart from these GoDaddy also lists other domains, but the expiring auctions at GoDaddy are the most popular. Based on the percieved value of the domain, domainers and SEOs bid on these auctions. If the original owner does not renew the domain, the top bid wins the auction and gets the domain name.
Thousands of domain names expire every day. The reasons are different. Some owners forgot to renew the domains, some just don't want them anymore or they moved on to other projects. For most people these so called Expired Domains don't have any value. They just see a bunch of Domain Names someone else deleted and move on, but for the people who know about SEO or the value of good Backlinks, Expired Domain Names are money just waiting to get picked up from the street. The only problem is to separate the good ones from the bad ones. That is where ExpiredDomains.net comes into play.