https://techcrunch.com/2019/03/19/apple-updates-imac-pro-options/

While Apple refreshed the iMac lineup this morning, the default iMac pro that you can buy for $4,999 remains the same. But Joe Rossignol from MacRumors spotted some changes in the configure-to-order options.

You can now buy an iMac Pro with 256GB of 2,666MHz DDR4 ECC memory — not storage, RAM. But that will cost you a small fortune as you need to spend an extra $5,200 to jump from 32GB of RAM to 256GB of RAM.