The Rat Market Saturation bit (as of 7/12) is all wrong
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The Rat Shilling payout is logarithmic past a certain point. Unless a FBG rep said otherwise that was always the plan after the Rat Ket reshuffle. It's easy to show experimentally regardless.
To show this: sell 3 T5s, 2 T6s, and then 2 T7s. If the guide/calculator was correct you would get 10395 Rat Shillings, but you don't. You get 10120 (that last T7 giving you 3850).
Then (on the next week or using an alt obviously) sell 4 T5s, 2 T6s, and then 2 T7s. According to the calc it would be 10560 Rat Shillings, but it's 10260 (with the final sale giving you 3825).