BackerKit for GURPS 2021 PDF Challenge came out. I got the $99 level which includes $125 of credit to buy PDFs. This is what I bought:

SJG 30-6005 GURPS Classic: Space 1E ($8)
SJG 30-6007 GURPS Classic: Horseclans ($8)
SJG 30-6012 GURPS Classic: Supporting Cast ($8)
SJG 30-6020 GURPS Classic: Time Travel ($8)
SJG 30-6039 GURPS Classic: Terradyne ($8)
SJG 30-6129 GURPS Classic: Best Of Pyramid 1 ($8)
SJG 30-6416 GURPS Classic: Villains ($8)
SJG 30-6509 GURPS Classic: Space Atlas 4 ($8)
SJG 30-6546 GURPS Classic: Vehicles Lite ($3)
SJG 30-7304 Floor Plan 4 - Mall of the Dead ($10)

SJG 37-0348 GURPS Action 5: Dictionary of Danger ($10)
SJG 37-0349 GURPS Steampunk 3: Soldiers and Scientists ($11)
SJG 37-0352 GURPS Monster Hunters Power-Ups 1 ($6)
SJG 37-0361 GURPS Dungeon Fantasy Career Guide ($5)
SJG 37-1634 GURPS High-Tech: Electricity and Electronics ($10)
SJG 37-1711 GURPS Disasters: Hurricane ($6)

And I still have $185 in Warehouse 23 store credit which maybe someday I'll end up using.