I usually do Rebus farm for animation rendering, works very well with corona.
If the jobs don't justify render costs, then I would consider reducing quality level based on budget. Low pay = low render quality. No raytraced renderer (gpu or CPU) can be done in super speed. ie. Either investing in tons of cores or a lot of gpus, getting render time down to 2-3 minutes per frame, it still takes up a long time for a lot of frames and a lot of electricity cost, hardware cost, or renderfarm cost. I would say the best option for budget rendering is realtime, either Unreal or Blender Eevee.