Edit - confirmed on Twitter.
Just saw this on Press Start. Maybe useful for those going next gen.
Between the 3rd of November and 9th of November, if you trade in your old console towards your next-gen preorder, you’ll also get double trade bonus for any games and accessories traded in as well.
- LEVEL 1 EB World Members – 10% Trade Value On Games/Accessories
- LEVEL 2 EB World Members – 20% Trade Value On Games/Accessories
- LEVEL 3 EB World Members – 30% Trade Value On Games/Accessories
- LEVEL 4 EB World Members – 40% Trade Value On Games/Accessories
- LEVEL 5 EB World Members – 50% Trade Value On Games/Accessories
EBgames will try to get you to spend all your trade in credits in store but you can always do your research and order some expensive item that you can preorder much later date and cancel it if this method helps.