Set a default price for variation

Hi there!

I was wondering if there is a way to set a default price for an attribute’s variation.

Let me explain: I have a poster shop, with three different size of poster. I have different designs of posters, but the price depends on the size only. For instance, A4 poster is sold $10, A3 poster is sold $20 and B2 poster is sold $30.

I have created an attribute with three variation (A4, A3 and B2) I would like to set a default price for each of these variation. Do you know a way to do this? It can be with a plugin but this would save me a lot of time!

Thank you!!

Manon