Kobo offered a limited supply of refurbished Wifi ereaders for $49, and promptly sold out. Just in case, though, there is a link where you can sign up to be notified when they get more (which is likely).
According to the website:
What is a Refurbished eReader? Its an eReader that Kobo has returned to its original specification and tested to ensure it looks and operates just like a brand new eReader.
So, be the first to know the next time they try this, and get yourself a bargain ereader.