There is a campaign running right now on ALL SAS operated nonstop flights to and from United States. It will run July and August and allows upgrade for cash with the following prices:

M->Y: $350
Y->C: $400
M->C: $700

I saw this on a printed paper at ARN check in (when upgrading for points).

The staff said it was new and was introduced to please US passengers (and I assume make some extra money). While she didn't confirm it in speaking it seemed like they are told to prioritize upgrades for cash before upgrades for points.