Maybe rewards for the higher buckets, ala Kickstarter?
Spend $180: Get a personalized, handwritten thank you note. Choose between Dan Scrawl or SF Chicken Scratch fonts.
Spend $360: A handwritten note from
both Dan and SF, plus an awesome t-shirt (may be pre-worn; size 5x tall only).
Spend $700: All of the $360 level rewards, plus an official Kosher Antarctica bentcher.
Spend $1000: All of the $700 level rewards, plus a genuine Antarctic Iceberg (may be slightly melted).
Spend $5000: One (1) penguin.