As IMR stated, the skin conditon is prime as well as do you still have the original box, manual, id card, all accessories and the battery, does it still work? Holes in the skin, splits in tail or neck, these are what people look for the most. After that, price is subjective and the one thing I can state, is that pleos in general, sell for more money this time of year, simply because people are more generous and looking for gifts for their children and themselves. If you could post a photo here it may help. Do you have any other things that go with him, clothes, collars, toys etc? I can give you an idea of what I think the Pleo could go for after posting a photo or and knowing the other items that come with him, orignal box and if the battery still works.
Are you just tired of him or getting another Pleo? How much was he or she used. Does he have a name and what operating system is he running, 1.0, 1.1 or updated to 2.0? Thanks and will look forward to photos and more info.
RedwoodsMama