What $/s means
Hatched Catboys pay cash every second. Reviewed nameplates and Index panels label that rate $/s. A first Common can be as low as $1/s. Catboy Tanjiro's opened panel was $5/s. The one Legendary panel that was opened, Catboy Sakuta, was $8K/s. Session HUD totals such as $45/s or $734K/s were that player's roster at that moment, not a stage requirement.
Spoken lines like worth $5 are easy to hear as a sell price. The on-screen unit in these frames was per second.
Spots
A reviewed cafe menu showed Cozy Cafe LV 1/12 and Spots 7 to 8. The next line was +1 catboy spot for $100K. Later spot prices were not on that frame. The $3M line on the same menu was Cat Wheel Tier 3/8, not the next spot.
The payback calculator on this site only divides a cash cost by extra cash you type in. It does not know which Catboy you will place, and it does not know the next spot price after $100K.
Selling
No completed Catboy sell screen was recorded. Egg cards do list Sells for amounts. Those amounts are on the egg, before or instead of a hatch, and they are not the Catboy's $/s.
Pass that touches income
2x Cash is a game pass priced at 149 Robux, pass id 2053912351, sold by Firstlight Studio. The pass description field is empty, so the name is the whole official statement. 2x Egg Hatch is a separate 149 Robux pass, id 2052346365.