What are you talking about? The most basic element of a fair market place (F.Y.I it is not competition) is that everybody plays by the same rule book. That rule book says that unregulated for profit business has no place on public land. If you want to be an entrepreneur do so under your own power and on your own dime. Don't mooch off the rest of us.
But I am not an instructor. I am a consumer of the goods and services that the ski industry offers. The reason for the animosity in this thread is due to a clash of interests. I am leaving the legality and ethics of the issue out of my comments now, as I already said my piece and won't continue to beat the dead horse.
Each party involved with the affair has their own vested interests in the subject. The instructors, resort, and Forest Service are in competition for the 'hearts and minds' of the consumer. The consumer, most of whom already have sticker shock at the prices of lift tickets, gear, and lodging, will naturally gravitate towards opportunities to save money. When faced with the oppprtunity to take a lesson for a lot less than the resorts demand, some will give it serious consideration, just as many will jump at the opprtunity to get discounted lodging or travel. The fact that it is technically illegal will simply be a technicality for many, just as buying a scalped ticket outside the stadium is technically illegal.
Getting rid of the scalpers is certainly the most efficient way for the seller to deal with the problem. As a consumer, however, I sympathise with the desire of some to want to save some money. Skiing has become a rediculously expensive activity over the years. Which leads me to the question of why people who need to hire a discounted lesson at Vail would be going to Vail to begin with. It's Vail-- you know the place is very expensive to begin with. Why would you go there? You can have just as much fun elsewhere for a lot cheaper. You can find quality instruction elsewhere for a lot cheaper. Even the stale, wilted hot dogs and watered down soda is cheaper at other places.
So, for folks who want a private lesson for a discounted price, here is MojoMan's El Cheapo' reccomendation -- Vail is the wrong place to be. Just go to a small resort on a weekday--a place like Pk n Pk or HV out East. Sign up for a lesson at a time when most people aren't around and chances are you will be the only one in the lesson. If you see a lot of people milling around the Blue or Black signs, go another time. Personally, I think a $600 private lesson is something I would never pay for, regardless of who it is from or where it takes place. I would rather have the money sitting in a CD or I would buy a pair of skis before spending $600 for a lesson. But I wouldn't go to Vail and then look for a discounted instructor, because it's still going to be relatively expensive.