I believe Cycles will be your best (or at least cheapest) bet, instead of investing into Indigo or Thea. – You can achieve the same results just within Cycles for sure. – What I came to like about it is that it allows for a lot of “cheating” as well. If you don´t rely on physically correct simulation only to achieve realism this is definetely a capable solution. – Also photorealism hardly ever comes straight out of a renderer, so also take a look at the built in compositor if you are not using any standalone solution for this already?
