Before talking about relative clauses, you have to fix several basic errors.
- Why did you suddenly choose 貨幣 instead of お金? 貨幣 is an uncommon academic term that mainly refers to physical objects to use as cash (e.g., banknotes and coins). It's not a suitable word when you talk about the importance of money in daily life.
- The use of 値打ち is wrong, too. First, 値打ち is a simple noun, not a suru-verb. Unfortunately jisho.org has a number of obvious errors like this one. Next, I think 価値 is better than 値打ち because the latter typically refers to a financial value, a value measured with money. It's perfectly natural to talk about the 値打ち of a jewelry, for example, but it's not very natural to talk about the 値打ち of money itself. (To me, the 値打ち of a 500 yen coin is always precisely 500 yen!)
- There is no single-word Japanese verb that means "to have value". You need to say 価値がある or 価値を持つ.
- 稼ぐ is wrong, too. It means "to earn (money, scores, etc)", but your sentence is not about earning money but about the value of money (you already have), right? This "make" is one of the English causative verbs. You have to use a causative form to translate this type of "make". For example, それに100円の価値を持たせる means "to make it worth 100 yen" or "to make it have the value of 100 yen".
Finally, we can talk about relative clauses. I assume you know the basic rule of relative clauses, so I'll write only the conclusion here.
One makes it have the value of 100 yen.
the value which one makes it have
I used 人, which can be used to refer to generic you (or we, one, people). With this, you can say something like this:
The value of money is the value which one makes it have.
Money is worth what we make it worth.
So, this is a literal translation, but this doesn't sound very natural. Probably most Japanese speakers can get the meaning after reading it several times, but it's usually best to drastically rephrase it to make it sound natural. Please see my previous answer for the examples.