Hmmm from you statement you want switch for"easy-to-use Cisco WS-C3560X-48T-S switch to enhance productivity by enabling applications for borderless network experience." and yet you want "to buy the cost-effective Cisco products."
While it is quite possible to get a good discount on any sites be it ebay, pcworld and any other you should also be wearies of refurbished equipment that could be sold as new. This is where the trade off come. Either you jeopardize your productively for cheap equipment or vice versa. Nothing good comes that cheap it effect on your production is all that will matter after all. But if it is just for your lab while not..ebay is one of the surest place to go. Cisco WS-C3560X-48T-S vs WS-C3560X-48P-S , worth it because from experience those switch are rugged provided you get it from the right source with smartnet though.
Hope this help this is just to serve as a guide as against the determining the dividing line between productivity and cost.