When you buy a cross country ski lesson you might assume that your instructor has some kind of ski teaching credentials. But more often than you would think, the “ski instructor” name tag indicates the person’s job, not their qualifications.
A cross country skier uses the ski poles for propulsion just as much as the skis. The ski poles' length, weight, means of attaching to skier's hand, grip, and pole basket, all have effect on the the effectiveness of a skier's efforts to move forward.
There is more to selecting the classic cross country classic skis than a price. There is a good chance that the classic skis in a used gear shop will not be suitable for learning or improving your ski skills.