The Goo farming is designed to be the most advanced crop.
For example the wild crop is spawned into elemental exo worlds. Assuming you’re happy to harvest goo on these worlds then you can start farming it. (You could also trade / buy seeds - if you don’t want to visit the worlds.)
The goo should be plentiful on these worlds - but it is also finite. As it’s a resource it’ll not regen. On the Testing exo it’s the second most plentiful surface resource. So there are huge amounts there.
The goo is also configured to yield the highest ratio of seeds to crops.
You can also mix the goo when creating the sprays - so no colour is really wasted. As long as the output colour is what you want you can often increase the volume with a collection of other colours. Mixing is important, as it’ll turn a collection of many different colours into a larger amount of a single colour. With careful balance you should be able to generate which ever colours you want.
The “edge” colours will be harder to create - because they can’t be created by mixing. But maybe you can find these wild on a world? Or maybe you have the gleam to mutate towards them? There are quite a few paths to explore.
You will definitely be able to generate much more than “a handful of blocks in a novelty colour”. Larger quantities are only limited by your endeavour and finding the most efficient way to create them.