Hi,
Well, you could create custom fields of the table "product" so that you would use their tag instead of a fixed price in the formula of the plugin.
For example, you could have a field with the column name "price_1900" and use the tag {product.price_1900} in the formula.
Then, in each product, you would just have to enter the price in each field.
And then you could easily change the prices with mass actions, or a CSV export / import of the products data.
Now, I understand you want to keep using variants and not go with custom fields because you've already configured everything in the variants. But in that case, you would need a custom item field to enter the value, and then add custom javascript code to the product layout to auto select the variant based on the value entered by the user. While that's possible, it would require hiring a developer to work on this.