The thing about goggles is that you have to put in a couple of days/hours of riding before you know what you like or don't like in a set. It is a little bit hard to know what to look for before you've done that, but here are some questions you can ask.
I call these the four fundamentals of goggles:
Do the goggles fit your face properly? Are they too big? Are they too small (which can limit your vision)?
Do they fit too high on your face because the cut out for the nose bridge is too small (which can mess with your breathing when you are breathing heavily) ?
Do they fit too low on your face because the cut out for the nose is way too big?
Are there gaps where the foam does not press against your face or your cheeks properly (this might mean that you need 'asian fit' goggles that have extra gasketing)?
Can you see properly out of the goggles? (check to make sure that you have a good field of view in both vertical and lateral directions)
Are the lenses double-paned? (pretty much a necessity for most conditions)
Do they have an anti-fog coating on the lenses? If not, do they need an anti-fog coating on the lenses? (some goggles do not)
Will the straps adjust to the proper size to accomodate a helmet or your head?
Do the goggles have to fit over prescription glasses?
Do the goggles fit below my helmet properly?
Are they more prone to fogging than other types of goggles
Are they spherical or cylindrical lenses? (This is not important to most people)
Do they have have adjustable venting in the lenses to help control fogging?
Are there different shades of spare lenses available for different conditions?
How easy/difficult is it to swap lenses?
Are the frames discontinued?
Do the goggles come in a micro-fiber bag you can use to clean them off?
Do the goggles come with spare lenses?
Do the frames come in a color that you like?
Are there lenses that come in a shade that you like?
Do the goggles make you look like an astronaut or a 1980's hot-dog skier?
In the end, it is the feature-set and trendiness that makes certain goggles cost more than others. Smith I/O, Oakley Crowbars, and Electric EG2's are some of the more popular top-of-the-line goggles. They sell for up to ~$180 during ski season, but regularly drop to half of that (or less) during off-season sales.
A ~$40 pair of goggles from a respectable brand will work just fine. YOu can usually get a better deal if you buy last-season's goggles from discount shops where they usually sell for half off and then you can use the money you save to buy spare lenses. I got some Smith Phenoms for $40 at Marshalls this past fall, and spent $25 on a clear lens for night riding.
Its always better to try on different sets goggles. Most ski shops have a pretty decent selection... but almost no one keeps asian fit goggles in stock.