Just picked this up today - got 6 $100 gift cards and 1 $50 gift card from the woolies deal below:
I went to the self-service and bought all in one go, came out to $552.50, then went to Rebel about 2 hours later and picked up the Garmin Fenix 6 Sapphire. You can buy a Rebel reusable yellow bag for $1 to use up the whole $650 amount in one go.
Hope this helps, credits to OP for the woolies post. Unfortunately you can't use these gift cards online so you'll have to pick it up at a Rebel store that has stock, of which you can check online. Also I called to check and there doesn't seem to be any issues using 7 gift cards, will just have to put it in one at a time. (Apparently someone had bought a treadmill before and used 20 gc's). Also I guess some people say that you can only buy 5 GC's from woolies at a time, but I was able to scan all in one go - YMMV.