I taught beginner skiers for 4 winters at Tahoe.
"if anything, just some long johns underneath. that + bib = good to go." Correct - you'll be sweating hot within an hour even if it's cold.
"You can probably get by with cheap wind/waterproof shells if you wear plenty of under clothes like turtle-necks, fleeces, long johns, etc..." I agree but I repeat, you'll be sweating hot ...
"If this is something you're rarely ever going to do again, then don't blow a bunch of money on clothes. Bibs from Goodwill would probably do just fine. Shit gets expensive with winter sports." You can even go to the thrift stores in Truckee or S. Lake Tahoe (Yellow Pages).
"I wouldn't switch it up much, 'cause you'll just be starting from the beginning all over again, and it takes a couple days to even begin to get a handle on things. Choose whichever one you're more naturally familiar with. Do you skateboard or wake board? Then try snowboarding. If you rollerblade then try skiing. If none of the above, try skiing. I think skiing is easier for beginners learn, but generally harder to master...or at least that's what my friends who do both always tell me (I've only skiied)." Ditto. Right now, start a physical conditioning program that includes balancing like rollerblades, skateboard, etc. Hop on one foot a few times, then switch to the other foot. Hop sideways over an imaginary line on the floor. Repeat till you're beat. Walk backwards up and down steep hills.
"...and if you're driving up to tahoe, consider renting the gear in your own town if you have a nice sporting goods place. Usually way much cheaper to rent there for a few days rather than day-by-day, or even multi day in the ski areas." WRONG. You don't know what correct-fitting boots are supposed to feel like, and you don't know how to adjust the bindings, and one size doesn't fit all, does it? And besides, a beginner package at the ski area may even be cheaper than renting crap in the city, buying a ski/board rack for your car, and then buying lift passes and lesson tickets at the hill. Read on.
"Pay for lessons, they're worth it." Cheapest + easiest + best way = go to the ski area indoor ticket sales and buy a beginner lift/lesson/equipment rental package. They will guide you thru the whole process, set you up with a lesson ticket, a lift pass and guaranteed right equipment. For example, if the boots don't fit correctly after an hour on the hill, or the skis are the wrong length, you can go back in and change for smaller or bigger. Try that with equipment you rented in the city. Hell, cry loud enuff that you hate boarding and they'll refit you with ski gear for the afternoon. After all, they're trying to hook you into becoming a repeat customer. Call the resort (ski area) beforehand and ask if you can do all this on the afternoon before your debut so you won't have to fight the morning crowds.
What, you say, you were going to drive up from the flatlands early in the morning, then somehow beat all the crowds to a parking space, a lift ticket, an equipment rental and still make it to a morning lesson? All this at close to 8,000 feet of altitude where the air is thin and your poor brain is oxygen-starved/befuddled? You ARE Superman/WonderWoman, aren't you. Get up to altitude the day before, relax, drink plenty of water (you'll get dehydrated anyway due to the altitude) and start to become acclimated so you won't be such an altitude airhead the next day. Lighten up on all the booze/drugs etc. 'cause you're at altitude. When you're lying in bed trying to go to sleep your heartbeat will be more pronounced (flatland vs. altitude) and will keep you awake. I like melatonin but roll your own (ExcedrinPM, etc.)
The next morning, your big debut, start by drinking twice as much water as you normally do because during the night the altitude and bone-dry air sucked you dry. A quart is good. It's cold in the morning, but don't get fooled. By noon it will be 30-40 degrees hotter so you will have to shed several layers. 10 degrees at 7:00am = 40 degrees at noon - too hot for all those winter clothes. make sure you can strip down to at most two layers, such as long johns under pants and a turtleneck under a shell. Don't wear slick, shiny outerwear - you can slide a long way on the snow if you do. Watch out tree! Don't eat that greasy bacon/egg/cheese fried breakfast - it won't digest well at altitude. Get some fruit and carbs.
Smile back at the ski area workers - if they aren't smiling, you picked the wrong resort. Yes, it will seem a lot like work to get all this accomplished and actually get up on the snow , but just keep in mind you're on the wrong side of the learning curve from the fun side. There's a reason why people become lifelong skiers/boarders and put up with all the hassles, and if you have some balancing ability and like the Great Outdoors, you just might get hooked too.