Setting up products with unique sizes

[makeaprint]

I am setting up around 1500 products that all have at least 2 different sizes, but not standard sizes e.g small, medium large, they all have there own unique sizes, for example:

product 1:    10cm x 15cm = £10,  17cm x 26cm = £14.50, 26cm x 45cm = £19.00
product 2:    11cm x 18cm = £11,  21cm x 29cm = £15.00
product 3:    10cm x 10cm = £9.50,  12cm x 17cm = £13.75, 20cm x 20cm = £18.50

Does anyone know a fairly quick walkaround of having a drop-down list on the product which alters the price that I can enter whilst creating the product?

[balai]

You can use custom fields. The cart variant type will be displayed as drop-down in the front-end