I decided to take this one step further to make sure it was a fair assessment. Below is a list of pads in the AP Racing CP8350 shape and the StopTech ST-40 shape. I'll focus on race pads, since those are the ones that will be getting burned up at a fast rate. Most people probably only change street pads once every other year. Nonetheless, if you search you'll find that any street pad is still considerably cheaper for the AP Racing CP8350's.
AP Racing CP8350-
AP Racing C300 Endurance= $189.84
StopTech ST-40: AP Racing C300 Endurance= $400.00
Difference=$211
AP Racing CP8350-
CL Brakes RC6= $201.60
StopTech ST-40:
CL Brakes RC6= $315.56
Difference= $113.96
AP Racing CP8350-
Ferodo DS2500= $127.99
StopTech ST-40:
Ferodo DS2500= $225.90
Difference=$97.97
AP Racing CP8350-
Ferodo DS1.11= $184.31
StopTech ST-40:
Ferodo DS1.11= $442.90
Difference= $258.59
AP Racing CP8350-
Ferodo DSUNO= $184.31
StopTech ST-40: Ferodo DSUNO= $442.92
Difference=258.59
AP Racing CP8350-
Hawk DTC70= $189.38
StopTech ST-40:
Hawk DTC70= $303.25
Difference=$113.87
AP Racing CP8350-
Hawk HP+= $109.81
StopTech ST-40:
Hawk HP+= $201.00
Difference=$91.19
Some other popular brands
AP Racing CP8350- PFC01= $182
StopTech ST-40: PFC01= $325
Difference=$143
AP Racing CP8350- Raybestos ST43= $173
StopTech ST-40: Raybestos ST43= $289
Difference= $116
AP Racing CP8350- Pagid RS14 Black= $238
StopTech ST-40: Pagid RS14 Black= $253
Difference=$15
AP Racing CP8350- Pagid RS19 Yellow= $266
StopTech ST-40: Pagid RS19 Yellow= $329
Difference=$63
AP Racing CP8350- Porterfield R4= $115
StopTech ST-40: Porterfield R4= $178
Difference=$63
Average AP Racing CP8350 price per race pad set= $180.10
Average StopTech ST-40 price per race pad set= $308.79
Difference= Track pads for StopTech's are on average $128.69 more per set vs. the AP Racing CP8350. If you want to plug those numbers in to my overall cost example in the previous post, over 5 sets of pads that's $643.47 more expensive to support the StopTech's. That's a set of tires, just on pad cost difference across 5 sets of pads!
Finally, please note that every single pad compound that I looked up for the StopTech caliper is also available for the AP Racing CP8350, and every one of them is cheaper for the CP8350. Finally, you're getting approximately 3mm more pad puck material thickness on each side of the disc with the AP racing set (20mm vs. 17mm).