It is difficuilt to say. You know eBay is a strange thing. I bought one PX-760SA retail at ebay for 100â‚¬ from a professional dealer with 2 years warranty. A week later a unused PX-760SA from a private person finished over 180â‚¬.
It may be possible a 1â‚¬ beginning auction will bring a good result. I saw it a lot that the 1â‚¬ auctions were often visited and finished with a higher result as a auction beginning with i.e 15â‚¬.
Maybe the other reason is the PX-760 is trhe last Plextor available on the market and the PX-755 not. The 755 was if I remember correctly not for a long time on the market and was fast replaced by the PX-760…