Inexpensive embedded/industrial system with PCIe x4 slot?

I’m looking for recommendations on small systems that hold one PCIe card, not just a motherboard. If you’ve seen Rack-Matrix/Broachlink/APU2 style systems, that’s the kind of small form factor system I’m on the lookout for. The size and cost of an OnLogic/Axiomtek/Lanner system is too much. I want to put a customized networking card in this system, and PCIe Gen 2 x4 is all I need. This Jetway might be close to what I’m looking for, but I’m not going to find it on newegg: Jetway HB651I215 | Intel Q670E, Alder Lake, Fanless System

I’m happy to hear any suggestions!

ROCKPro64 4GB Single Board Computer - PINE STORE and a case?