WooCommerce: Cart price override with text

We have a bunch of products with either:

• No price
• Zero price

We made them purchasable with the built-in hook but the cart still displays them as having a 0 price during checkout.

We'd like the cart & checkout summary to display "Special order" or any other text, but it seems WooCommerce invalidates text-based prices.

Tried this : WooCommerce: Add product to cart with price override?

The above works fine with a number override, but when tried with a text override it defaults back to displaying a 0 price.

Why? These products are built-to-order and the shop admin will update price after talking to customer/supplier.

via Chebli Mohamed