Money is a crucial civilisational technology. It solves the double coincidence of wants problem and enables specialisation and commerce.

A self-sustaining Martian civilisation is impossible without it.

Also why do you assume a single colony?

To me, the most attractive aspect of Mars is that a group of (30-50 couples / families) will be able to establish their own village anywhere on Mars and make their own rules.
No government. No boss.
No taxes.
Many different possible social organisations.

They will be able to be self-sufficient in most things and just trade for the lightweight Earth produced electronics etc.