As a grandmaster who uses Paladin++ in his army, I should be able to give a good feedback. I think Paladin is great in defense, because it supports every single champion in your army from the begining. It is surprisingly good in offence in late game. Give it some turns and you might attack the enemy king while devastating the rest of its army.

Unfortunately, I can't really compare this with actual price and moveset of units now, since the game won't load, so take these suggestions only as tips.

A lost it's ability to attack from distance, but it should be suprisingly good with it's teleport+unblockable attack combo. I'd agree with rxu on giving it the cost of 15. Yet, I'd rather use my Paladin++.

B has the worst moveset of all, but it's ranged attack can't be blocked - which sounds great, but I can't really see this piece in battle. I'd agree with e3gewinnt on giving it a cost of 11. You might make it more powerfull by improving it's moveset.

C is interesting, I would definitely give it a try. I'd expect surprising unblockable attacks from this unit. It has good moveset, but it is very fragile with its little defense, especially against close enemies. I'd give it price 15 or so. I would like to see how this unit works with armor - might easily surprise enemy king if the player does not pay attention. That would greatly improve it's price.

D did not seem interesting to me at first, but I'd like to see this in battle. It might be too easy to predict it's moves, but I can see it's potential in always being able to come back and save your king, even swap with another unit or easily promote your minions! (with no support, though) I'd need to see this in battle to see how it works and to give it a fair price, but I can see it somewhere between 16-20.