Try to find some people local who will let you try some skis before you buy.
If not, you may have to buy something in your price range and go make friends (you have sit downs so you should be able to get out and find people.)
The ideal ski would be superjet (free ride) or sxr (race).
Budget being an issue, you may have to settle for an older superjet (free ride) or 750sx (race). You could also consider a 650sx. 650sx is a good 1st ski. Stay away from 300sx, 440, 550 and x2. If you have to buy a ski that isn't ideal, maybe put a pipe in it but other wise don't spend any money on it and save for what you really want.
The most important thing is condition. I will take a super clean worry free 650sx over a worn out and busted 750sx. It's no fun to buy your 1st ski and never get to ride it because its always broken. Clean and reliable is the most important. If you can't afford something in good condition, buy nothing and keep saving.