GET A HELMET - around $100 - Helmets aren't geeky any more. In fact, they're cool. Actually, they're rather warm. There are now many styles and brands to choose from. Some even come with air vents. Finding one that fits is very important so spend some time and do your research. Trees don't bend like slalom poles and rocks don't usually move. I'm not going to harp on safety, but this is now probably going to be your most important equipment purchase.
Balaclava - around $16 - I recommend the Seirus brand headliner. It's medium weight stretch Thermax fabric is very comfortable, warm, and very inexpensive. I also recommend the Lifa brand balaclava which is made of thin polypropylene. I use it only on cool days. Both don't affect the fit of your helmet very much.
Heated insoles - around $190 - Got cold feet? If your boots aren't heated, get a pair of heated insoles. These heaters have a small heating element that warms your toes. There are a couple of different brands that work very well. Hotronics offers two models. One for custom insoles and one that includes an insole that you cut to fit in your boot. The battery has 4 settings and recharges overnight. Simply run the cord up the inside of the back of your boot. The batteries strap on or clip on to the back of your boot.
Wigwam Ultimax socks - $16 - These are the best ski socks I have EVER found. The inside is soft terry cloth with no toe seam. They stretch snuggly around your foot and don't move. This means no more crunched toes! They are a little pricey, but they're worth it since they last for many years. I use the thermal weight during the winter and the light weight during the spring. They are very hard to find, so if you find them, try a pair. The only place I know that has a large supply is Lahout's in Lincoln, NH.
Fanny pack - $12 and up - Fanny packs store all the stuff you keep in your pockets or purse, like keys, discount cards, change, etc. They come in many different sizes and styles. Some are pretty basic with one storage area, while others come with many and may include a water bottle.
Waterproof fabric - You don't have to spend a lot of money to stay dry. There are other waterproof fabric makers that aren't as expensive. The key thing is to get a jacket and pair of pants that have waterproof fabric, not a waterproof coating. The coating doesn't last as long and you'll get wet when you least want to.
Boot dryer and warmer - around $27 - No more waking up in the morning and finding wet boots. At the end of the day, open up your boots, insert the heating tubes, and plug them in. The convection heat thermally drys from the inside-out, and without removing the liner. In the morning, your boots are dry AND warm.
Skigee - $2 - This little plastic gadget acts like a windshield wiper for your goggles. Slip it around your thumb and wipe back an forth. It clears rain, wet snow, and frozen drops off your goggles without harming them. You can usually find these at base area ski shops.
Smith Snow Eraser - $2.50 - After getting snow inside your goggles and trying to find something to clean them off with, you'll wish you had one of these. It's made of an absorbent, non-abrasive sponge that wipes away snow and water and a soft, synthetic chamois that gently dries the lens. It comes in a perforated bag for storage and can also usually be found in base area ski shops or your local ski shop.
Seirus Cat Tracks - $15 - Save your soles! Your boot soles, that is. If you boot-up at your vehicle then walk to the lifts, these will come in very handy. Made of soft plastic, these traction devises hook onto the bottom of your boots. They help prevent slipping on ice and snow and help extend the life of your boot heel piece. * TIP - They come with a storage bag, but it's too small. Put them in a Ziplock type bag so you can stash them in your fanny pack when you get to the lift.