I think it makes more sense to compare the prices after adding the FSD (Fully Self-Driving) option. You can buy the same car but with AP and FSD brand new after tax credits for $47,250.
New Model 3 LR with FSD:
$43,000 Model 3 LR
$3,000 Autopilot
$5,000 Fully Self-Driving
-$3,750 Current federal tax credit
Total= $47,250
Therefore the used car with AP and FSD should be 90% of $47,250= $42,525 but including AP and FSD. In other words, instead of paying $47,250 for a new Model 3 LR with FSD, somebody could buy the same car used with 1,000 miles on it for $42,525 because the 10% discount would be worth it to some people.
Assuming this car doesn't have Enhanced Autopilot, adding Basic Autopilot and Fully Self-Driving would cost 2+3=$5K. Therefore the price should be $42,525 -$5,000= $37,525 if it doesn't have EAP. If it has EAP, then adding FSD costs $2,000. In that case, the price should be $42,525 - $2,000= $40,525.
I think these are the maximum prices you could ask for because this method maximizes the value of the car by making use of the advantageous AP and FSD upgrade prices for used Teslas. That's how much the used car would be worth to somebody who wants FSD but not everybody wants FSD. Most people would be happy with the new basic Autopilot. Therefore we can calculate how much it would be worth if somebody wants EAP or AP but not FSD. In that case, the price of a new car would be like this:
New Model 3 LR with AP:
$43,000 Model 3 LR
$3,000 Autopilot
-$3,750 Current federal tax credit
Total= $42,250
Assuming the car doesn't have EAP, adding basic AP would cost $2,000 (you can't add Enhanced Autopilot anymore). Therefore the calculation would be 0.9*$42,250 - $2000= $36,025.
Assuming it has EAP, I think the difference between EPA and AP is worth a $1000 bonus. The old EAP is better than the new AP because it includes (1) Navigate on Autopilot on the Highway, (2) Autopark (3) Basic Summon. In that case, the car would be worth 0.9*$42,250 + 1000= $39,025 if it has EAP.
Car doesn't have EAP: Worth between $36,025-$37,525
Car has EAP: Worth between $39,025-$40,525