The MagBag 2 costs $49.99. The product is well made and certainly useful, but a basic sandbag's a lot cheaper. Even just buying one of those recyclable grocery bags that are so popular these days and filling it with a couple of pounds of dried beans will do the job in a pinch, so if you're on any kind of a budget, you would probably have trouble justifying spending $50 for it. Still, if you're not worried about how much you spend on photography, this is a well-made, well-designed and useful product for a variety of situations.
Trek-Tech provided an evaluation unit of this product for the David Busch Quick Snap Guide to Photo Gear.