If you take a look at the AppleCare+ for Mac page at Apple’s online store, you can see that clicking both iMac Pro and iMac links bring yo unto the same AppleCare+ for iMac page. Despite the fact that there is a big price difference between the two machines, you get AppleCare+ coverage for the same cost of $169.
Take it into perspective. Even if you were to buy a full decked out iMac Pro that costs over $13,000, it’s cheaper to buy the AppleCare+ for the iMac Pro than it is for the MacBook or MacBook Air ($249), even cheaper than the iPhone X ($199).
AppleInsider made sure to check from various regional versions of Apple’s website, including France, Germany, Canada, and UK, to see if the prices would be higher, different, or same. After checking, it seems that the prices were the same across all online store. At this point, it’s unclear if this was a mistake on Apple’s part of it they choose to change the price in the future.