For a desktop, 10 Gbps PCIe NICs are not expensive, especially if you go for used ones on eBay. For a laptop, the Thunderbolt adapters are still expensive, but

For a desktop, 10 Gbps PCIe NICs are not expensive, especially if you go for used ones on eBay. For a laptop, the Thunderbolt adapters are still expensive, but 2.5 Gbit adapters are very cheap if you can handle that limitation.