The difference between (a) http://www.web-rich.co.uk/salespages/70scripts.php and (b) http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=5118409935 (while it lasts) is that (a) provides the name PhpDig and they also make it clear that they are reselling the software for download, so a quick Google search will net you a PhpDig download for free.
However (b) hides the fact that they are reselling PhpDig and they also state "Sie erhalten unsere Lizenz übertragen für das komplette Suchmaschinen Script" and "Wir benachrichtigen den Hersteller das Sie unsere Lizenz übernommen haben" in their auction. These quotes mean "you will receive their license, transferred to you, for the complete search script" and "they will inform me, the manufacturer, that you took over their license" respectively. Huh?
That's the difference.