Did you look on
E-bay? Yes, on-line sales have even reached the world of industrial process equipment. And if you buy a less expensive model with some hours on it, it will be a small investment to see if you can set up a manufacturing process to make what you want.
However, not all
feed material that you pour into a pellet press will form satisfactory pellets. It has to have some sort of binder in it that will cause all the solid particles to stick together when they are put under pressure. Some natural materials have
enough sticky material in them to do so, but if they don't you can always add something like paraffin wax.
The first experiment you would have to do is to take your feed stock and put it in a press (recording the time and temperature it was under pressure) and see how much pressure it takes to make a pellet. That's the first spec you need for your machine. If time, temperature, and pressure are all high values, then the next experiment is to see what kind of binders you can add to reduce the values to something that is feasible for your process.
That's my suggestion for how to get started, now happy shopping.