You can purchase all the tools instead of renting them. Someone on reddit did the math and found it was $1100 to buy everything.

https://www.reddit.com/r/hardware/comments/uuocl3/the_verge_...

To confirm it, here's all the Apple Tools listed for the iPhone 12 Battery Replacement. All costed at $1086.96.

    # Apple Tools  
     $49.00 [7-Day Rental] iPhone 12 Tool Kit (Part RKIT-12) [Rental Information]  
      $0.65 Back Protective Cover (Part 923-04877)  
      $0.65 Display Protective Cover (Part 923-04878)  
      $0.70 Adhesive Cutter (Part 923-01092)  
      $2.78 Nylon Probe (Black Stick) (Part 922-5065)  
      $8.00 JCIS Bit (Part 923-0246)  
     $10.00 Super screw Bit (Part 923-02066)  
     $12.00 Micro Stix® Bit (Part 923-01290)  
     $13.33 Torx® Security Bit (Part 923-0247)  
     $29.50 Display Adhesive Press Plate (Part 923-04911)  
     $50.00 6.1-inch Repair Tray (Part 923-04908)  
     $80.00 Torque Driver (Green, 0.45 kgf cm) (Part 923-00105)  
     $85.00 Torque Driver (Gray, 0.55 kgf cm) (Part 923-00738)  
     $99.00 Torque Driver (Black, 0.35 kgf cm) Kit (Part 923-0248)  
    $108.00 6.1-inch Heated Display Pocket (Part 661-19620)  
    $115.00 Battery Press (Part 923-02657)  
    $216.00 Display Press (Part 661-08916)  
    $256.35 Heated Display Removal Fixture (Part 661-17619)