I bought everything brand new from RackAttack.com which I found to be the least expensive at the time.
Parts I needed:
Yakima FatCat 6 ski/snowboard carrier (holds 4 snowboards or 6 pair of skis) - $179.10
Yakima Q Towers (1 pack of 4) - $135.00
Yakima SKS Cores/Locks (6 of them, one for each of the 4 Q Towers and one for each of the 2 FatCat6 racks) - $58.50
Yakima 48 inch cross bars (1 set of 2) - $58.50
Yakima 44 inch fairing - $58.50
Yakima Q7 clips (2 packs of 2) - $63.00
Total = $552.60 (Shipping was free, thank goodness)
It can be sort of hard to imagine, but this is how it works: the Q clips physically hold the entire roof rack assembly to the car. The Q7 clips are actually made for different car models, but I chose to custom mount my rack for a more secure and flush fit and that's what the recipe called for - you basically cut, bend, and paint them (Here's the link I followed: How To: Custom Installed Yakima Rack - NASIOC
). Otherwise, you'll have to get a different model Q clip and the rack would mount between the glass and trim around your windows I think - which seems like a horrible idea to me - and it's supposedly a weaker way to mount it. The Q clips hold the Q towers to the car. The Q Towers support the cross bars. And obviously the ski/snowboard carrier, fairing, and/or any other accessories you want to have mounted to your car mount on the cross bars. It's sort of inconvenient that you have to buy the lock cores separately, but it's a really good idea to have them because if you don't, anybody could walk by your car and pop off the little plastic plugs where the locks would have been installed and remove the whole thing pretty easily - and as you can see, it's not cheap. At least the SKS (Same Key System) ensures that you only need one key to operate all the locks - and if you need a replacement lock cylinder, one can be made according to your specific key, so they should always match. Even if you buy some or all of it used, you're still talking about several hundred bucks. There are ways you can do it cheaper, like obviously buying parts used, or omitting the fairing, opting for a less expensive ski/snowboard carrying unit, or omitting the lock cores. You can also go with a different brand, which can sometimes be cheaper. That's just the setup I chose to go with after some research and good personal experience with Yakima products in the past.
After one complete winter season having it mounted, I noticed that the insides of the ends of both crossbars have developed a little rust because the plastic end caps don't completely seal the bars from the elements. I tried to sand off as much as I could and smeared a dab of grease on them to help prevent them from rusting any further, but that almost seems inevitable. Worst case, I'll have to buy a new set of crossbars and cut them to length again - not too big of a deal. The Q Towers and ski/snowboard carrier are in excellent shape. The carrier, itself, has a few dead bugs on the front of it, but it really didn't seem to fade very much after being on for a few months and sitting in the sun. The fairing took most of the abuse from bugs and other debris. It has a fair amount of nicks, scratches, and dead bugs on it - which I might just cover up with stickers this year. Other damage included a cracked plastic crossbar end cap and a broken core clip (thin metal piece that holds the lock core in place), so I had to order those for everything to be fully operational this year.
So add to the previous total:
Yakima Replacement End Caps (set of 4) - $8.00
Yakima Q Tower Lock Housing Clips (set of 4) - $3.60
...and a roll of clear electric tape (several bucks more) which I'll use as a layer of insulation underneath the foot pads of the Q Towers to keep them from contacting my roof paint directly this year - the paint was moderately scratched last year from the Q Tower feet contacting the paint directly. I was able to buff almost all of it out using rubbing compound, but I'd rather not have to do that again. During the entire winter, I never took the rack off to clean it, so that could partially be my fault, but I prefer to have the rack be a once-and-done thing for the season once I put it on. I plan to put down a little more tape than I need and then carefully/neatly trim it with a razor blade so it doesn't show.
Hopefully I've answered most of your questions, but if you have any more, feel free to ask.