Try Commerce -> 25% discount + Autocracy -> 33% discount + Big Ben -> 25% discount.
A riflemen unit costs about 250 gold then. A nuclear bomb about 550 gold
It's fun.
Autocracy usually comes too late though.
This is probably my favorite aspect of autocracy right here, plus the fact that all of my armies have really cheap upkeep. I find that autocracy works well on larger maps that require larger armies in the late game, as well as having a tall base(1-5 cities) empire and large puppet empire.
The games I've used it in were for pure fun, and not for any optimal victory time. For instance I've had the best synergy with these civs: Germany(I once postoponed the research of rifles until industrial era, then bought a ton of Landschnekt and upgraded them, kind of silly but it was really fun seeing the majority of my army just pop up out of nowhere essentially.
) Persia, but mostly because I rigged the Total War policy with a 20+ turn golden age on a standard speed game, that was REALLY FUN,.The Aztecs have the tools to use it effectively as well, a friend has shown me this, but I have not actually played an Aztec autocracy game. Russia can use the coin and extra strategic resources to rush buy a ton of nukes and elite units, and I've been meaning to actually try that out. I've used it to great effect as Songhai as well, especially in rushbuying an airforce as I continue my intercontinental conquests throughout the ages. I've used it as Japan before, but ultimately it seemed like a bit of a waste, given the Japanese UA effectively nullifying the advantages of a cheap replaceable army.
Definitely fun in the right situation, but for more standard play i'd still keep liberty and freedom. I feel that you must PLAN for an autocracy strat unlike some of the other policy trees.