If you want something that actually lubricates he chain and don’t mind a dirty chain, car gear oil as recommend by chain makers themselves – the thicker the better. The thickest I’ve found cheaply is Comma EP85W-140 GL-5 1 litre from Wilco @ £4.99 Wilco. 330 cSt at 40 degree C.
So that’s £4.99 per litre against (e.g.) Finish Line at £70 odd.
Are you riding them or just storing them? If storing then a thin dry lube should be fine, if riding then depends what conditions you’re riding in – wet lube stays on longer but usually attracts more gunk. Stuff like Muc-Off C3 wet and Purple Extreme are a good compromise, generally staying pretty clean but also lasting well.