Since it is your first pair of skis and your budget is pretty low ($400 will barely buy you a new pair of Marker Jesters), I'm going to say that you should visit your local ski swap when it comes around anytime from mid-September - mid-November. There's a common misconception on ski swaps -- that they include only used, crappy gear -- which isn't true. Ski swaps normally include about 70% new gear from local shops -- usually the previous model year -- and 30% old, used gear from individuals. In addition, ski swap pricing is very low -- 50-75% off MSRP in most cases. For new gear, that is probably your best option, unless you want to buy online. The disadvantage of ski swaps is that often, you won't find the exact ski that you want (although you will find your second and third choices in all likeliness). You really have to go in with an open mind.
For used gear, I would recommend the B/S/T here on NS, except you're a n00b, so people will probably refuse to sell to you. That and the B/S/T is pretty scam-ridden anyway.
That covers your method of buying. Now how about some more information in order to recommend a ski? East/west coast? Home mountain or home mountain's avg. annual snowfall? Groomer, powder, park? Do you want a rockered or reverse camber ski? How many days do you ski annually? etc., etc.