Ethernet cable advice

Where to buy a good one, not a very expensive if it's possible? Would be really grateful for recommendations.

It's quite hard to give a good recommendation when we don't have an approximate knowledge of stores around you.

In general though, most electronics shops will usually have a significant markup on items. If you can find a general surplus store, they usually have fairly good pricing on them, if they have it available.. As long as you're getting a Cat5e cable, you're doing fine, those support speeds upto 1gbps, and that's where most motherboards max out on network speeds.

I got some good value ones off Amazon, far cheaper than the stores in my city

Flat cables are good also. They are durable and easy to manage.