I find that generally if you want to get the ski you want for a decent price, it is right after ski season ends. Most shops and online retailers still have a fairly wide selection of ski/length combos so you can usually get what you want specifically for like 50% off.That being said, if you wait till the start of the next season you will definitely get better deals on last seasons equipment, but your selection will be much worse. You may find the ski you want, but in the wrong size ect...
Ski-swaps at your local mountain are still probably the best way to do it though.