Under $20 is fine for an 8GB DDR4 stick.

Probably $15–25 for a reputable brand like Crucial, Kingston, or Corsair. Anything over $30 and you’re being ripped off.

DDR4 is a mature, well-understood technology. The big names all use the same few memory chips from Samsung, SK Hynix, or Micron. You don’t need to hunt for “gaming” RAM or RGB lighting. A plain stick with a heat spreader (mostly cosmetic at these speeds) is perfectly fine.

Check your motherboard’s max supported speed (usually 2666, 3200, or 3600 MHz) and buy whatever matches that. If you’re just adding one stick to existing RAM, aim for the same speed and timing as your current kit. If you can’t find an exact match, you can mix brands — worst case the system will just run everything at the slower stick’s speed.

Don’t overthink it. This is not where you get performance gains. It’s just memory.