I've used desktop forges to fabricate PCBs and other parts to make my own top tier commlinks. Mind you, I merely borrowed the use of one, i did not actually buy one.
In the case of using them to make components to then assemble into valuable things like high end commlinks, I would say they'd be worth it, and pay for themselves in a short few months. But that's if you can cover the rest of your overhead for things like guards, fronts, bribes, and "Clean" feedstock. So that could add up to a much bigger headache then just getting some suppliers for the components themselves, maybe not, it depends on where you are and the scenario you have to work with.