Domain names are important, and some might even say that a premium, memorable domain name is priceless. It’s become increasingly difficult to argue against businesses scooping up those short, relevant, easy-to-remember domain names when they’re available. Doing so can give your business, customers, and search engines a simple and quick way to find your business, along with the bonuses of brand protection and a potential increase in traffic, not unlike prominent placement in the yellow pages or the local shopping mall for brick-and-mortars.

Thus, to some, making a big purchase on a coveted domain name seems ridiculous, while others have dreams of other-worldly click-ability and traffic that enables massive ROI. Whichever side you fall on, companies have become increasingly willing to spend big on premium, recognizable domain names, as evidenced by the Domain Name Journal’s list of the top domain name purchases of 2011. The biggest purchase in 2011 was, unsurprisingly, “social.com,” which was co-brokered by Moniker.com’s John Mauriello and Marksmen’s Cyntia King on behalf of the latter’s new sales division at NameQuiver.com.

According to DN Journal, only two domains were sold for $1 million or more in 2011, with the second being “DomainName.com” for a cool million. However, in early January, Robin reported on the first big domain name purchase of 2012, which went to “dudu.com,” bought by a Dubai-based social networking service provide called DUDU Communications.

Today, we’ve learned that ViSalus Sciences, a direct sales “health transformation company” that distributes weight management and nutritional supplement products, has entered the shortlist of pricey domain name buyers. The creators of the so-called “Body By Vi Challenge,” which (among other things) is a 90-day contest that offers people health products, support, and cash prizes in an effort to incentivize them to achieve their weight loss and fitness goals, announced today that it has acquired “challenge.com” and “vi.com.”

Together, the domain names were purchased by ViSalus for $500,000 and $325,000, respectively. The purchase of “challenge.com” alone is one of the top ten most expensive domain names bought in 2011, through today. At a combined value of $825,000, the two domains together would be the fourth highest purchase over that time, and individually “challenge.com” and “vi.com” are the second and third most expensive buys of domain names this year, behind only the million-dollar “dudu.com.”

So why did ViSalus shell out all this cash for its two new domain names? According to Co-founder and CEO Ryan Blair, the company just announced a seven-fold year-over-year sales increase in 2011 to $231 million, which means that the purchases represent a fraction of a percentage of current sales.

Obviously, this means that, for all intents and purposes, ViSalus now owns the word “challenge” online, and Blair says that with the acquisition of “vi.com,” the company has gained a “simple, multilingual brand architecture” that can help them work towards creating a global, household name.

The company’s goal is to acquire one million customers before the end of 2012, and Blair thinks that putting the new domain names to work will help speed up “the viral nature of the Body By Vi Challenge.” The move is meant to complement the recent launch of The Challenge, a newsstand publication that features Body By Vi success stories and is expanding into Canada this month.

It’s a lot of money to dish out to promote healthier living, but with Americans spending upwards of $50 billion on products and services designed to help them lose weight and stay in shape, there’s certainly plenty of demand for the type of platform ViSalus is building, and owning the word “challenge” on the Web certainly doesn’t hurt.

For more, check out ViSalus at home here, or the list of recent big-ticket domain purchases here.