I don't have a source on hand, but I've read a bunch of reviews and articles over the years pointing to the need for binning for low power to make the high-end versions of T-series chips work out. While these articles rarely if ever really explain or attribute this to a specific source, it makes logical sense - it's harder to maintain a set performance level with strict power limits than it is to push performance when power is less limited.
As for pricing, I probably confused no-letter SKUs for K-series SKUs, you're likely right there. I might also be a bit biased form living in a small country where the tiny market for T-series CPUs generally means they're really expensive. Still, Intel doesn't list retail MSRPs, but only OEM 1000-unit tray prices, which don't necessarily relate that closely to retail prices (both as retail packages often contain more than just the CPU and come with various distributor markups and so on, and as large OEMs generally have a lot more leverage to bring prices down).