Personally I will only buy pants 20K or higher, although 15K+ is probably sufficient. I definitely wouldn't go any lower than that unless you plan to buy new pants every season, use waterproofing wash/spray regularly, and don't do much hiking/sitting/falling.
17 Jones Storm Chaser . 16 Never Summer Swift . 16 Rome Pow Division ST x Snurfer . 16 Gnu Swallow Tail Carver . 15 Never Summer Snowtrooper BIA
17 Burton Malavita Wing . 16 Burton Genesis X
16 Flow Talon . 16 Flow Hylite