History of the Daleks #2 has been back in stock for a little while. I sent an email to GOGS1 a little while back and they said the other Dalek Sets WILL be back in stock this year. For a brief moment, the Amazon listing said 'In Stock March 1'' and then immediately reverted to not in stock. So I am hoping these will come in March, and I am checking regularly.
I do believe there may have been some shipping delays. But I fully expect (hope?) the two sets will come in. After all, the two Tardis sets went out of stock, and then back in stock. Same with the Witch's Familiar sets.
(Otherwise I'd be really peeved on passing on the chance to get slightly reduced HOTD Sets 3 & 4 from Ebay that are currently selling)