While most people are familiar with Groupon and LivingSocial as flash sale sites, there is a whole other segment of the online flash sale genre that may be lesser known, which include the likes of fashion sites Gilt and Haute Look.

The genre of fashion flash sale sites developed as a way to score expensive goods for a fraction of the price. The catch? The sales are limited to a certain time frame (sometimes up to 48 hours) or until the item sells out. This “act fast” model is perpetuated by a constant stream of emails sent to members, which can aid or persuade members in to making quick decisions about purchasing items. These sites require membership and use email to send notice of different sales starting.

Some of the more popular fashion flash sale sites include Gilt, Haute Look, Ideeli, RueLaLa and Beyond the Rack. These websites bring designer fashion goods to members for a steeply discounted price, without which the members could never afford the items.

Gilt, one of the aforementioned flash sale sites, has also diversified itself into a variety of niche categories in an attempt to better cater to their member’s needs. This includes Gilt Home, Gilt Children, Gilt Men, Gilt City, Gilt Taste and Jetsetter. Gilt City, Gilt Taste and Jetsetter are direct competition with the types of deals Groupon and LivingSocial provide their customers including food, drink and travel deals.

 Flash sale sites have grown exponentially in the past two years, but these growths have apparently slowed down. CNN Money reported “spending on flash sales rose 21 percent last year, according to American Express Business Insights, which tracks the spending habits of its 90 million cardholders. While that’s still strong growth, it’s a far cry from the 92 percent gain these sales saw a year earlier.”

A reason for this decline in traffic to these flash sale sites may be because sometimes better deals can be found at discount designer online stores. For example, Stephanie Rosenbloom of the New York Times reported, “On HauteLook.com…a navy dress by Decode 1.8 was $75, plus $7.95 shipping. But at Overstock.com, the dress cost $55.99 and shipping was free. Savings: $26.96.” The dramatic difference in prices can be partially attributed to the higher-than-usual shipping costs employed by these flash sale sites. Most of these sites utilize shipping fees between $7.95-$9.95, which contrast with shipping fees from discount designer websites Piperlime.com and Bluefly.com, which usually charge below $5.00.

While the designer products found on fashion flash sale websites are sometimes exclusively found on that website for a discounted price, it is important for prudent shoppers who want to find their designer brands for the cheapest price to do total bargain hunting and shop around.

 Several discount designer websites are alternatives to flash sale websites and directly compete for the same target market with the edge of low shipping fees and easy returns. A few notable designer discount websites include Theoutnet.com, Overstock.com, Piperlime.com and Yoox.com.

Another tool for designer bargain shoppers is ShopStyle.com, which is a fashion search engine that provides shoppers with a variety of discounted designer items. The web browsing toolbar add-on Invisible Hand can be downloaded by shoppers and used to see if the item you are shopping for was found at a cheaper price on another website.

While fashion flash sale websites can be a great way to snag designer duds at a low price they are certainly not the only website with a discount.