what is the cheapest/quickest way to get from Krackow to Slovenia
Mary, unfortunately, when travelling from Krakow to Slovenia you can't use cheapest/quickest in the same breath. The cheapest would be rail but involves a minimum of 15 hours riding the rails. The quickest would be flying to Ljubljana via Munich at a much higher cost.
Me, first I wouldn't do it because there is too much to be missed between the two, but if you must then fly via Vienna for something less than $500.