what method of postage to use that qualifies for seller protection

[boysstuff11]

Hello - which is the best method?  So far I have used my own packaging but recently have sold bundles of clothes which attract exorbitant postage costs.  I could use a 5kg satchel but the issue there ofcourse you only have tracking and not the postcode printed on the receipt so no seller protection.  Sending it that way would make it viable for me to sent outside Vic to other states otherwise the same item in my own packaging costs about $10 more....what is the cheapest way to send things interstate whilst qualifying for this 'seller protection'??  Also, congrats to all sellers out there, such a time consuming and trying endeavour selling on line is...tricky...many thanks in advance for all of your help.