I've seen a lot of digital cameras being offered at very low buy it now prices, often well below their high street price. I've even been tempted to bis on one or two, but being the cautious (read paranoid) buyer that I am I always look into what is being offered. What I've found is that most are SCAMS.
The first thing to watch for is the description If it doesn't have the word "NEW" in it, it's eather second hand or what the seller will call refurbished. many sellers seem to try to overload you with information (you basically get the entire marketing brochure for the camera), with a one liner in a smaller font at the very end of the listing stating that it is a refurbished products. Many of these are imported from outside the EU, so may not be the exact specification you are expecting. Most of these won't have a manufacturers warranty despite what the seller advertises.
The second thing to watch for is where is it shipped from, and also where is the seller located. If either are outside of the EU then chances are that the product will be a grey import, and again will have no warranty.
Thirdly check what accessories you're getting. Many cameras come with their own batteries and charger. If no charger is listed it's proably due to two things: 1. It's stolen or 2. It's not a UK product.
Finally, and this goes for any ebay bid, read the entire listing. I've seen plenty that list the condition as Mint, Excellent, or Near new, but in the fine print will be a problem "LCD screen cracked, but still works great", or "Thinks Lens cover is on".
Hope this helps!