PBS currently has a sale where quite a few titles are just $5.99 (about 70 blu-rays, 300 dads). Use code MEGA
https://shop.pbs.org/mega-sale?itm_source=shoppbs&itm_medium=cms&itm_campaign=banner_MegaSale5.99_May12&N=1540625023+162738988&Nrpp=28&No=0&Nr=product.active:1
For example, you can...
I suspect the Lost In Space deal was similar to a lightning deal (although I didn't see it labeled as such).
I ordered at that price, but later in the day I saw the higher price
I'll cancel whichever ends up with the highest price come release day (actually a few days before).
Price guarantee will apply on each.
Originally I just had the single 2D ordered , but with the combo drop, I'm locking in that price, just in case.
No downside having both on pre-order.
It is interesting that the 3D/2D combo of Ant-Man is $19.99, while the 2D only version is still $24.99.
I have both on pre-order, since I only want the 2D, but will take the eventual lowest price