Your best bet in terms of cost, is not to use RJ45 as this works out very expensive. Mellanox ConnectX-3 cards can be had on ebay in about the £50 range, these can then be used with SFP+ DACs, which are cheap cables for devices close together (
https://www.fs.com/uk/c/10g-sfp-dac-1114 ) or with cheap 10G SFP+ MMF modules (
https://www.fs.com/uk/products/11552.html ) for linking longer runs.
If you want/need to stay with copper for a particular run, you can use RJ45 DACs, these are much more expensive tho (
https://www.fs.com/uk/products/66613.html for 30m, 80m ones are ~£65)
I have a 10G mellanox card in both my main PC and my server, and a cheap 10G switch (
https://linitx.com/product/mikrotik-...1g-4s+in/15664 ) that links the two, and provides a 1G port linking to the rest of my network.
The Mellanox ConnectX-2 cards also work well, and are even cheaper, but are very old now, so not much updated driver support for them.
10G networking is really good, and it means I can do things like have all the storage drives in my sever, and use iSCSI to mount them, meaning my desktop can be in a smaller case with no spinning rust. Very glad I upgraded.
I get pretty decent throughput as well: