clabers.com, is offering very good service which is "Trade Alert". This service provide facility to members to receive Trade Alert by email for specific category for Sell offers / Buy Offers / Products / Company or ALL. So whenever any member post Sell offer, Buy offer, Products, company in particular category so members will receive notification (Trade Alerts) by email. No need to visit website again and again for searching required products.
You can subscribe Trade Alerts from Members Area ------> Misc ------> Favorite categories