What do you mean by 'they are a member of SaleHoo'? Are they a verified supplier and part of the directory or the site owner is a SaleHoo member? We tried searching our database but somehow we're unable to find them.
Anyway, I did a quick check. They have been online since April 2008 and are based in Hong Kong. Although they accept PayPal (which is considered a safe payment method) I would not encourage you to buy from them. They use a free email account as their contact email (although they have a contact us page). Also shipping orders as gifts is not very ideal and should not be done by a true wholesale supplier - if your package gets into the hands of Customs you may have to face serious consequences.
Like you said, their DS prices are so low so you're questioning the authenticity - maybe this is a sign telling you to look elsewhere.