[solved] Additional Price variant Fields, e.g. Cost

I have a customer that would like to also record variant prices for costs, e.g.

Simple product:
Price = R1000.00
Cost = R900.00

Variant product:
Price [novideo] = R1000.00
Price [video] = R1200.00
Cost [novideo] = R900.00
Cost [video] = R1100.00

I thought that by adding the custom attribute "cost" to the Variant Field list in the Product Type would do the trick, but it doesn't.
Product Type
Variant Options:
[x] Price
[x] Cost

Doesn't seem to work. Is this even possible, or just tell the client it's not.

I only now realised that the QuickEdit only has the price field, it would be nice to have the "cost" field as well.

In the Variant Editor, it is there, so this is resolved.