Farther down the page it talks about T2 Unlimited pricing, which is the same thing here. It does look like it needs to be updated to include details for T3 as well, however.
I'll submit some feedback to the documentation team about getting that updated.
Pricing varies from region to region, on-demand vs. reserved instance, etc.
The general answer is they are cheaper than the same sized t2 version.
(Disclosure: I work at AWS, not posting in an official capacity)