Went in to that store to check on something and found these starter packs at half price. According to the store guy, this deal is only at that store. I bought 6 of them with no problem but he could process only 2 per transaction, so was done in 3 transactions. I will use them to switch between providers.
And before you ask, you cannot use them to recharge the existing boost connection every month. You can port your number out using a $2 sim (don't use Telstra SIM cards) and then port it back to boost using one of these starter packs.
Hope someone will find this useful.
Thanks OP