whistler and the coastal range is heaven on Sleds!!
consider saving up and getting a 2005 and up, so many advances happened in the mid 2000's you will be left behind on anything older or it will be hard as shit to ride.. you want a good mountain sled, long track, deep lugs so you can get up the mountain in deep pow to do runs. or heck just ride the sled cuz its just as fun if you like gas powered toys! and whistler is the best place in the WORLD to ride snowmobiles
All the sled brands ride different too.. might eb worth while riding a few to see what suits you.. but honestly.. you wont go wrong with a used 2006 to 2009 Arctic Cat M8 or M7.. very reliable.. i just bought my second Cat.. and they both run killer.. the older M6 has 4k miles and runs like a bat out of hell still, and i ride'r hard!
make sure you bring your muscles and never EVER! ride alone..
its costly $$ but all the powder riding you will access once you know how to ride will be your payoff..
powder snob here, but the only time i ride variable/groomed/hardpack conditions now is when i take my 6yr old boy snowboarding at the skill hill to teach him. i only ride powder.. pFFFFt!