i just picked up a nice board for $150 from craigslist. If you have a buddy who has been surfing for a while, ask them to help you check out craigslist. Most of my shortboards are from craigslist or second hand from pros who come out here for the winter then just sell their boards after. I feel like craigslist best sales are surfboards (I do live in hawaii though might have to do with that)
but 700-800 can get you a very nice board...$1200 you can have one shaped to your exact specs.
I assume you have surfed a bit before..in that case you should know what size your looking for. Like previous posters-wide and thick are better for beginners and summer swells.
if you can tell us more about your surfing experience and where you are surfing we can probably give some advice.