Similar to StarHub, M1 won't be taking pre-orders for the iPhone SE. Instead, the phones will be available to purchase from 31 March. Prices are that much different from the other two telcos, with the lower tier plans requiring an upfront payment.
Typically, you'll be looking at the plan that gives you 3GB of data, on top of 200 minutes of talktime and 1000 SMS, which'll cost S$42 per month. That amounts to an upfront payment of S$365 for a 64GB iPhone SE and S$215 for the 16GB model.
If you're hungry for data, signing up for the higher tier plans gets you a S$0 iPhone SE. But take note, M1 also has a data add-on option, which could potentially cost you less in the long run if you combine that with a lower tier subscription than forking out more every month.