Right now Antminer S9 in decent condition is available locally. I have some, but considering getting more. I am saving up for a M30S or S17 running somewhere around 40 W/Th. Used S17 prices seems to hover around 55 USD per Th and Whatsminer about 80 USD (but warranty included).
I think its better to buy efficient gear, even with cheap electricity like yours. You will certainly be able to mine longer in case of price fall/diff growth and the equipment itself will hold value for longer time. When those s9 become unprofitable at 6c, not much people would find them useful (except someone with free electricity), which will eventually make them worthless. With an s17 however, you will be able to mine longer or sell it.