As cool as this sounds, and I would love to go, I have to say that unless you are SUPER into being on board with Shatner and the astronaut you could get this same quality trip much cheaper.
Any trip that goes on land (not all do, anything I think over 200 people just sails around looking) will include some visit to a penguin rookery. They are super cool and also extremely smelly.
Most trips that have landings also include some historical sites, or research centers. and lectures.
I didn't go on a trip with a submarine but someone I know did, and there is really not much to see down in Antarctic waters, it's pretty murky stuff (which is also why there are so many whales of all kinds and seals and things, rich with nutrients). So I'm not sure it's worth paying for this extra, as opposed to something like camping out on land or being able to ocean kayak.
But I think the people who do spring for this will have an amazing time even if the price is steeper than I'm willing to pay! I would never look down on someone willing to trade money for an amazing and unique experience, and this is definitely that.