Dobizness.com offers a very good alert service which is "Trade Alert". This service provide facility for members to receive Trade Alert by email for specific category on Sell offers / Buy Offers / Products / Company or ALL. So whenever any member posts Sell offer, Buy offer, Products, or Company in a particular category, members will receive notification (Trade Alerts) by email. There is no need to keep visiting the website again and again to search for required products.
You can subscribe Trade Alerts from Members Area ------> Misc ------> Favorite categories