While looking at domains, you might come across the name "ICANN" -- the Internet Corporation for Assigned Names and Numbers. This organization accredits some registrars that agree to a set of operational standards, but ICANN accreditation isn't required to sell domains, nor is it necessarily a sign of a company with good customer service. In fact, ICANN plays no role in the sale of many top-level domains, including country-specific domains.
The top ten was rounded out by #8 Ecig.co.uk ($6,613 at DomainLore.co.uk) and two more Sedo sales - #9 Wallace .co at $5,999 and #10 Poianabrasov.ro at $5,632. Sedo went on to sweep 16 of 20 chart entries overall. UnicDomains filled three spots with sales they made on the Above.com Marketplace with their marquee sale of #4 AR.ca ($25,000) joined by #12 (tie) Playground.ca ($5,000) and #20 BlackMarket.ca at $3,500. 
Sedo went on to sweep the first eight chart entries and 17 of 20 places overall, including another six-figure home run with #2 Jobster.com at $200,000. Their haul also included the other two ccTLDs in the first five - #3 GolfTV.co.kr at $69,600 and #4 (tie) GolfTV.kr at $58,000. Bobet.com shared that #4 spot with GolfTV.kr by attracting $58,000 as well.
There are numerous domain name registrars. Listed below are just a few, along with my comments, if I know anything about them. Note that the domain name industry is highly competitive, with prices wildly fluctuating throughout the year, every year, so it's impossible to really mention accurate prices below unless I spend all my time updating this page. Please check their sites for the latest rates. All prices below are in US dollars.

Even if the term isn’t trademarked, don’t buy domains that are just a variation of another domain name. This means avoiding plurals if the singular is taken (mediatemple.net vs. mediatemples.net), hyphenating a phrase (media-temple.net), or adding “my” or some other preposition (mymediatemple.net). Alternately, you might consider buying these variations yourself and set them up so that if someone types one of the variations, they are redirected to your main site.

In order to register any domain, you must provide certain personal information that you may not wish to be publically searchable in the Whois database. Signing up for WhoisGuard is a great way to keep your registration data private. WhoisGuard acts as a "shield" for your searchable information, displaying the address, phone number, and email of the domain registrar (Namecheap, e.g.) instead of your own. Keep in mind that WhoisGuard is an optional security add-on that must be renewed separately when you renew your domain.