I would also recommend watching the [Marketplace] [Goods] section as well as [Auctions]. Occassionaly you can find a decent raffle under [Marketplace] [Gambling] [Games and Rounds] too such as this one that I'm entered into.
https://bitcointalk.org/index.php?topic=713625.new#new*note, these are literally gambling and there is no garuntee that you will walk away with anything for the satoshi's you throw at it. Luck of the draw type of stuff.
S1's are absolutely rock-solid though. Self-contained, not real noisy imho and stable as stable can be. Highly recommended. S3's also reasonably priced and offer far better wattage/GH ratio if you don't have reasonably cheap electric.