Some credit card companies offer the ability to split purchases up over 3-6 months such as Chase and American Express. Check yours.
Also PayPal and some companies offer those 4 month payment plans that don't impact credit or charge interest.
Many ski shops allow you to put on layaway.
Lots of options, but tbh shouldn't need to use money you don't have to buy skis. Just save the old fashioned way rather than making a financially irresponsible decision. Or buy used or during black Friday.