I received an email from Oneplus on 12/15/15 Tuesday with the following message

"Our Very First Weekly
Open Sales Start Today!

Join us every Tuesday for chance to get the OnePlus X invite-free
Starting at 16:00 CET or 4:00 pm PT, you have 24 hours to purchase the OnePlus X without an invite."

I went to the Oneplus website page
https://oneplus.net/
and OnePlus X is available to be purchased without invite for $249.00. That is just for the phone. Different styles of protective case available with each case costing $24.99

Typically purchase is only possible if you have an invitation for purchase. Hence some may see this as a deal as no invite is needed for purchase for those certain period mentioned.