When bidding on a particular game it is essential to understand exactly what is being offered from the seller.
Popular games if not all go Platinum (or Players Choice). This means that the games has been on the market for sometime or is very popular. As a result of games going platinum they are often sell for less. Due to this occurance, sellers can buy these products cheaper and sell them for more on ebay.
A way of noticing platinum games is that they are differently packaged. Before you bid make sure you check your items packaging to that of pictures on a search engine.
Original packaging items are then actually worth more money due to the unavailability or purchasing new, plus platinum games stick out like a sore thumb in your collection. That is why i prefer to buy ONLY original packaged games. Overall the quality game play of original to platinum games are identical but ask yourself, why would i pay more for a game on ebay that i could get in a second hand games shop?
At the end of the day however, the choice is entirely up to you!