I have a 2023 Prius XLE AWD and My total cost to add an OEM spare to was $596.14, I followed a write up on the Priuschat forums. I don’t know if the 2024 is similar or not.
You could probably get away cheaper if tried to make your own foam inserts. I already got burned by having a flat in this car and the piece of mind of having a real spare is great. I didn't know car makers were moving away from spares so it was a shock to be stranded on the side of the road with only the little compressor and tire goop cartridge...
From Toyota OEM Dealer Parts site:
Protector, Spare Wheel Carrier -- Part Number: 51978-47010 -- $33.04
Wheel, Disc -- Part Number: 42611-21280 -- $70.64
Box, Deck Floor, LH -- Part Number: 64997-47100 -- $86.95
Box, Deck Floor, RH -- Part Number: 64995-47080 --$141.74
Carrier, Spare Wheel, RH -- Part Number: 51931-10040-- $12.37
Protector, Spare Wheel -- Part Number: 64778-47090 -- $141.74
Flange Nut (Three) -- Part Number: 90178-A0132 -- $2.70
Box Set, Jack -- Part Number: 09105-47020 -- $87.45
Subtotal $576.63
Discount (Haul in the Holidays Promotion) -$133.58
Shipping & Handling $47.09
Grand Total $490.14
Tire off Amazon:
T145/90D16 -- $99.00
$7 Dollars to have tire shop put spare tire on wheel and inflate
I made a video of the install: