The basics are simple: Skis/snowboard, bindings, boots and poles. If you plan to buy equipment it is a good idea to rent or demo first to find the equipment best suited for you.
Prices vary but plan on about $40 per day for the basic rental package: boots, snowboard or skis with bindings and poles. The price is less for multiple-day rentals and many shops offer free overnight storage for your rental gear.
Boots should be snug, but never painful. Skis should be chosen according to your height and ability and poles should be tall enough to be held vertically to the ground with your forearms parallel to the ground.