The maximum input current to IoTaWatt is 50mA. All of the CTs sold at the stuff site have 50mA output at their stated primary current. So the ECS16100 is 100A/50mA, and both the ECS1050 and ECOL09 are 50A/50mA.
If you tell me what you are looking for in terms of how many 100 and 50 Amp CTs, I can quote shipping to Australia. Since you already ordered your unit from OEM, you can’t take advantage of the $20 flat rate shipping from the stuff site as others down there have.
For example, since you can get a decent AC adapter and USB power supply locally:
1 IoTaWatt @ $119(US)
3 ECS16100 @ $11 = $33
6 ECS1050 @ $6.38 = $38.28
2 ECS1050 @ 8.50 = $17
Total $207.28
Flat Rate Shipping $20
Total $227.28(US)