I have a great way to easily buy all of the upgrades in the store instead of playing multiple games trying to grind out weapons/specials/ship upgrades.
This method uses your cloud save to allow you to keep reusing the same ship upgrade tokens.
1. Play a few levels, about 5, until you get a total of 15 upgrade tokens. At the beginning of the next level, press start, and quit out to the main menu. This makes sure that our save syncs to the cloud.
2. Press the Xbox dashboard button, highlight the game, press start, press manage game snd add ons. Now go to saved data.
3. Press delete all, and then press delete all again (may have additional menu prompts, just keep deleting save). This deletes the save from your console, and does not impact your save in the cloud.
4. Reload the game (save from the cloud will auto sync), go to campaign, pick whichever difficulty you were on, press continue.
5. When you start back up the top left of your screen will show 1 upgrade tokens. So go ahead and kill 1 enemy, collect a green orb. Now you will have the 15 upgrade tokens (or whatever number you originally had). Now let yourself die again. When you die press “Garage”.
6. Now upgrade whoever gun/special/shop upgrade that you need.
7. Repeat steps 2-6 until you have all ship upgrade achievements.