If you go with a race stock ski, look for a 180ish ski from previous years. Rossignols are the softest, Volkls are a bit stiffer, Dynastars are sort of middle of the road, Head is getting up there and the big boys are Atomic, Fischer and Nordica. Which one you choose will come down to preference. But I would recommend a softer ski for someone starting out, especially at the tip. A 21 m + ski does not initiate turns that easily, and many people have trouble making them work at first. A softer ski can help it roll onto edge.
The other option would be a 180ish club racer GS ski, with a 17-19 m radius. This option would definitely be the easier way to go, and once you get used to the length, you can move onto a race stock. Look for models from Atomic, Fischer, Head and Volkl, although many good skis are out there.
The worst thing you could do is buy a ski that is too stiff, too long and too straight. That is a great way to blow an entire season with little progress made.
If you want a deal, I recommend putting some time into looking on ebay. That's about as cheap as it gets. You can get a lot of last season's GS skis for under $300.