If you buy a lot from eBay then this site can be a good tool to you. This site offers all latest auction updates via sms. Ebay also offers this type of service but that cost around $0.25 per auction for mobile alerts via text message.

GSM mobile phone tracking system via the GPS-TRACK satellite network
Based on repeater triangulation, the system tracks mobile phones using GPS and GSM technology
We are not responsible for possible tracking errors that may occur.