I have an SVS SB12-plus that is in excellent condition. I still have the original box. I believe it weighs around 45 or so lbs so be aware that shipping it might not be cheap. If you are in Colorado then local pickup would be preferred.
Great subwoofer especially for a small to medium sized room... very accurate.
Please make sure that you reply to this thread if you are interested as that is the only way I will be notified of your interest.