MSY have a Sandisk 128GB UHS-II for AUD279 which is the cheapest I can find. The CFe cards are really expensive in comparison. If you find something cheap(ish) then let me know. I do know that CFe card readers are mostly out of stock especially the dual prograde CFe/UHS-II around the world.Sorry. I was thinking in Australian dollars. 256Gb card is 500-600 AUD.
On top of this, we still don't know what CFe cards are approved by Canon for the R5. The Sandisk USH-II is the fastest available and would be fine. The Sandisk CFe 128GB is not approved for the 1DXiii