This months didy of the month is Jan-- it is 20 dollars off the regular price. Every month David has a special Didy that is for sale at a lower all month long.-- If you go to http://store.attachedtobaby.com/detail.aspx?ID=139&Name=Didymos-Stripes it will explain the Didy that is for sale better I can BUT we normally find out which Didy will be for sale earlier by a special puzzle David creates
HTH
here are more links for ya https://www.attachedtobaby.com/forums/thread/10089.aspx
https://www.attachedtobaby.com/forums/thread/11192.aspx
https://www.attachedtobaby.com/forums/thread/8264.aspx
and past Didy of the month topics
https://www.attachedtobaby.com/forums/thread/7864.aspx
https://www.attachedtobaby.com/forums/thread/6700.aspx