A YCH based on inflation.

Red, sold. MP5SD3 of FA
Blue, $3 starting bid

Any gender, almost any species. Here, blue has convinced red to inflate themselves with the mystery substance that Blue knows what it is, but not red.

Bidding ends Tuesday, Noon EST, December 23rd. Payment should be made within 24 hours of close of bid.

Also, $10 is the "buy now" price for each spot.