A little update to this thread about a fabulous deal I found which is working great for me whilst staying away from home temporarily. Vodafone Prepaid 365 Plus. How it works: You can buy 2GB each day for $3, and if you Recharge each day the unused data rolls over. But, even better, on Friday, Saturday and sunday you get 4GB for $3. So, essentially you get 20GB a week for $21. If you Recharge at any time today, it lasts until midnight tomorrow night. So for 28 days you get 80GB for $84. Also if you need extra data on a particular day or you are running low, you can just recharge again... so you could do two lots of 4GB on a Friday, for instance.
Obviously the catch is that if you forget to recharge you lose your accrued data. I usually recharge first thing in the morning. I've put the sim in my Android phone and using that as a hotspot, it just sits in the corner and does the job. Very pleased and happy with the service.