Its fun because you can create your own shapes and use your imagination to create aquascapes.
I've actually gone beyond that and have used foam, pvc etc. to create a bridge, wall and island
But if you think DIY rock will supplement LR and save you tons of dollars, you might want to think twice.
Many of the DIY LR people have sumps full of LR rock and rubble.
I am of course talking from my experience and am no expert but everyone has their own opinion and if you put in the time to research and you do it right (patiently) it should work out for you like it has for all the others...
HTH