I took the reins in 2009 and planned our ski trip myself. I did it again for the 2010, 2011, 2012, 2013, 2015, and 2016 ski trips. After the 2009 and 2010 successes, I figured it might be a good idea to document what I did for anyone else who's curious. It's pretty expensive, but it's worth it if you can save up for it way ahead of time.
The graph on the right is for 2009 through 2016, but the following text is just for 2009 and 2010.
The first thing to do is pick the dates for the trip. Our 2009 trip was the week of Mardi Gras and the 2010 trip was during spring break. We left home on Saturday and returned on Saturday, which means 7 nights in another bed.
The questions of when and where should be answered together as some resorts close earlier than others. Spring break trips may not work if spring break is late and the resort closes early. In 2009, we wanted to stay and ski in Breckenridge, but also drive to Vail and Beaver Creek for some variation. In 2010, we chose Telluride because we'd never been. It's comforting and fun to revisit the resorts we are used to because we know what to expect, but it's always nice to see what else is out there.
There are 5 essential purchases: plane tickets, rental car, condo, skis, and lift tickets. The car can be avoided if there's good public transportation or a shuttle service straight from the airport.
Usually about 440-540 $/person (round-trip) to get to Denver. I got tickets for 430$ in 2009. To Montrose in 2010, it was 465$. I start looking early at priceline.com and watch the ups and downs of prices. There's really no pattern that I can tell. If you watch them long enough, you can tell when a low price is a good deal or if you should wait. Also important is times of departure and arrival. You need to make sure you can get to the airport and the condo in time.
When to reserve: 4 months before
There's a free shuttle bus from the Denver airport to all the car rental places nearby. Thrifty seems to be the cheapest. It costed 225$ for an economy car for the week with unlimited miles. (Gas was extra.) Denver airport to Breckenridge is 100 miles. (About 2 hours in good weather.) It's not recommended to carry your skis inside the car (as opposed to on a ski rack), since they act as projectiles in an accident, so getting a ski rack might be something to consider. Also, the car might not be long enough to hold skis.
As for Telluride, there's a shuttle service from Montrose airport that is slightly cheaper than getting a car, just under 205$ for two people. Definitely worth considering if you don't intend on driving anywhere.
When to reserve: 1 month before
The very cheapest 1-bedroom condos in Breckenridge run between 950$ and 1600$ for 7 nights (pre-tax). I was looking at Tannenbaum in Breckenridge but ended up with Snodallion (1225$). It's a short walk from the main lift on Peak 9. In Frisco, 8 miles toward I-70, prices at the hotels can be half that price, but it's a cold drive to find parking every morning. Besides, Breckenridge is much prettier than Frisco.
Another thing to consider is whether or not you want to cook meals in the condo. Not all condos come with a kitchen.
When to reserve: 4 months before
Blue River Sports in Breck is pretty good: 18$/day, 5th day free, 10% off when reserving more than 10 days ahead. They can store your skis for free, which might make sense if it's on the way to the lift. Black Tie in Telluride was double the price at 36$/day.
When to reserve: 2 weeks before
Oddly, I think you're really just paying for the lift. Skiing is free, but who walks up the mountain? Ticket prices depend on how many days you want to ski. 3 of 5 days was 255$, 4 of 6 was 316$, and 5 of 8 was 365$ (73$/day). ("3 of 5" means you can ski 3 days within a 5-day period.) Tickets are good at any Vail resort: Breck, Vail, Beaver Creek, etc. A Telluride 5-day ticket was 415$, or 83$/day.
When to reserve: 2 weeks before
For some people from the South, a day of instruction in a class would be a good idea. It looks like that costs 106$ at Breckenridge and includes a limited lift ticket. (I guess what that means is you have to be with the instructor to get on the lift.)
In 2009, it costed us about 700$ to eat and drink all week. We ate out more than we could have, so the price was higher. In 2010, it was only 575$, but that was a different town. Prices vary.
For the two of us, it all added up to about 3920$ and 4140$. An average of 4030$. Again, not cheap.
Out-of-towners get especially screwed. We have to pay for plane tickets and condos where locals don't. Those two expenses are easily 50% of the cost of the trip. Also, we usually can't get season passes, which are generally tons cheaper than day tickets.
Per person, it's probably at least 200-300$ if you go really cheap (like me). I really have no idea exactly. You can definitely spend a lot more if you get higher quality gear.
Here's information on the layers and materials to look for. I'll be brief to give an idea of what to wear so you aren't miserably cold and sweaty. Tips have been taken from Ron LeMaster's book, The Essential Guide to Skiing: 201 Things Every Skier Must Know. Here's one: keep your core warm. This will let more heat/blood get to your extremities.
The time of year determines how much clothing is needed. By the time spring rolls round, you can get away with a lot less.