LCG stands for Living Card Games, I guess it's a gimmicky way some company found of saying "ccg that doesn't expect you to re-mortgage your home". Basically, the base set box (40$) contains at least one copy of every card in the set. Then they come out with these boosters every month that also contain at least one copy of every card in that mini expansion (10$). It's 20 cents per cards if you're just buying one box set. If you want playsets of every single cards, the cost goes up to 50 cents per usable cards (not counting the cards you'll then get more than 3 copies of, which you can donate to friends or use as cutters for pot). That's still a very fair price.
Warhammer: Invasion came out last month and I'm a huge fan so far. I honestly prefer this new business model. Random booster packs are very 1994.