Cheapest 10gb 1 Port PCI Express network cards (NIC) RJ45 inc. Low profile – NAS Compares
Dell Intel X540-T2 Dual Port 10GbE-T Rj45 Ethernet PCIe Card | Intelligent Servers UK
10Gtek® 10GbE PCIE Network Card for Intel X550-T1 - ELX550AT Chip, Single RJ45 Ports, 10Gbit PCI Express x4 LAN Adapter, 10Gb NIC for Windows Server, Windows 7/8/10, Linux: Amazon.co.uk: Computers & Accessories
Intel X540-T1 1 Port 10GbE PCIe Server/Workstation Network Adapter Card LN61760 - X540T1BLK | SCAN UK
Dell Intel X550-T2 Dual Port 10GB RJ45 Network Card C4D5P