You could consider the seat from OpenWheeler. It retails for $199 (USD) and has the appearance of a racing seat with the side bolsters but it does have a cutout for center-stick mounting and comes with sliders that support mounting to aluminum extrusion.
https://www.amazon.com/gp/product/B092LMYYYM
The listed images are of the older version without the center cutout but a few folks have reached out to their customer service recently and they confirmed they are shipping new orders with the cutout found in the listing for their full cockpit:
https://www.amazon.com/gp/product/B0BPMN53GW
Hope that helps!
You should get the simfab rig like this one that I got. I love it. Super comfortable, configurable, and solid. And it didn’t break the bank quite as much.