Ok - allow me to defend this product.
We needed an OSCommerce integration with Joomla done over a Saturday/Sunday. Initially we balked at the price, especially compared to EJoomCommerce. However, we found that although EJoomCommerce is nearly there (as of August 1st, 2006) and will probably be production-ready soon, we needed another option.
Marcin was really helpful. He took us through the benefits and explained that it took a long time to integrate - hence the price. I think the price is $50 for a self-installation and $250 for Marcin to do it. That fact isn't well explained on their website or here.
Our client was paying extra for speed and professionalism and they got it from this product.