i am wondering about this too. rebrickable has parts lists which you can upload to vendors of alternative bricks. however that is actually not that much cheaper

i am wondering about this too. rebrickable has parts lists which you can upload to vendors of alternative bricks. however that is actually not that much cheaper. you may get the bricks for half the price but from tests i made, about 10% of the bricks you need are not available as alternatives, so you'd have to search them on bricklink where they will be more expensive because the missing ones tend to be the more special and less common ones. so in the end it may not be worth it the effort. you can get clones of original sets which obviously violates lego's rights, but what i am curious about is that there are alternative instructions for existing sets. that is, you can take a set and use those instructions to build something completely different. now, what if someone produced and sold a set with those different instructions, you buy it and then build the other set using lego's original instructions.