Anyone checking domains will soon see that the suffix or extension determines the price you pay – .coms are usually the most expensive of the popular suffixes, while .co is the most expensive of all.
So why pay more? Shouldn’t you just buy a .info or .biz version of the domain?
The answer lies in the plans you have for the site.
If you are just building a hobby site or a personal blog, perhaps the cheaper domain will suit you. If you are determined to get a particular domain name, but the .com, .net and .org versions are gone, then pick up one of the other suffixes.
But if you plan to get good ranking for your site, and make money from it, and be taken seriously, the three top suffixes are .com, .net and .org.
Some search engine optimization writers believe that the search engines favor those domains above others in their rankings, particularly .com. In my experience, it is very difficult to get a .info site to rank well, and to get any decent traffic. Even the .co I tried has had disappointing results.
So, buy a .com if possible, otherwise .net or .org. You will notice this very site follows this philosophy!