In reply to Y Gribin:
Simple economics. If they sold out of stock last year, then they either aren't making enough or didn't charge enough. The correct response is to make more, charge more or do both until they find the limit of what their customers can bear.
Alternatively, last year's prices might have been loss-leading and, with a place in the market now established, it's time to make a profit!!
As a small firm, Jottnar won't be as resources- or data-rich as giants like Arcteryx so expect similar instability for a few seasons yet.