As skies are the main piece of equipment required for your holiday I would say a BIG YES to your question.
Hired skies can easily cost £60 for a week so in 2 or 3 years they have paid for themselves and you don't run the risk of getting issued poor quality gear. Nor do you need to queue on the first day to be issued your skies that can some times lose you a whole mornings skiing.
I would say no but i'm no expert. The cost of new skis and teh hassle of maintaining them each year. At least if you have hired skis you don't have to worry about damage to them.
If your skiing once a year I would say don't bother, the hassle of maintaining them, the extra cost of carriage etc makes it not worth while.
I've skied for 25 years and bought a pair when I first started but they were more hassle than it was worth. I hire my skies and when they need waxed or get gauged I just take them back and get them changed.