In no particular order:
1) The starter pack should be re-buyable every 30 days.
2) 30-day heat amp for 5000 CE
3) 24 hour elevator pass (removes CE cost from elevators) for 250 CE, or a permanent elevator pass for 2500 CE per tier (must be unlocked in sequence, unlimited T3 access would require unlimited T1/T2 access as well)
4) Exchange 20 of any one crafting material and 1 CE for 1 of any other crafting material of the same tier.
5) Medic trinket for 250 CE, reduces CE cost when reviving others by 50%
6) Permanent weapon/trinket slot upgrades for 1500 CE each
i like only the permanent weapon slot upgrades idea. The PERMANENT ELEVATOR PASS isnt good idea. I mean if you buy 1 for each tier that makes 7.5k Ce but you will probably spend much more energy doing it without that permanent pass so i think that will never happen.