Noun and の adjective
はりがね
もし値ごろ感が重視されるのなら、我々の針金が圧勝することになるだろう。
If affordability is a necessity, our wires will win hands down.
A needle made of gold is a wire. Perhaps wires were made from gold mostly back in the day? And they were thin like needles? That's my guess.
The reading is the kun'yomi reading of both. You've learned 針 already, but 金 is more like お金, rendaku'd.