Hi,
Not sure about the health insurance not having applied for this visa before (someone else will know for sure), but for cheap tickets I always go with STA travel here in Aus. I used to buy my tickets on Webjet, the last time I went in January I paid $1,900 return (on Emirates). Now I've just bought a one-way ticket to Paris for November and only paid $700 at STA (on Etihad).
I'm not sure how you go about getting a flexible return date, but if you can get a cheap price one-way you might consider just buying a return flight separately when you're there. Maybe contact STA and they'll be able to help you out.
Not sure about the health insurance not having applied for this visa before (someone else will know for sure), but for cheap tickets I always go with STA travel here in Aus. I used to buy my tickets on Webjet, the last time I went in January I paid $1,900 return (on Emirates). Now I've just bought a one-way ticket to Paris for November and only paid $700 at STA (on Etihad).
I'm not sure how you go about getting a flexible return date, but if you can get a cheap price one-way you might consider just buying a return flight separately when you're there. Maybe contact STA and they'll be able to help you out.