Definitely, age is always a factor in most of the things we are involved in and football is no exception to that. A perfect example is Sergio Ramos; one of the greatest defenders if not the greatest is not even able to play 4 to 5 games consistently without getting injured meanwhile in his youthful age he was one of the strongest amongst the players in a team , putting in dangerous and hard tackles and still came out of them feeling like nothing happened.

The same cannot be said now, playing full 90 mins in a game will potentially mean that he will be out for the next 3 games.

Another example is Cristiano Ronaldo who was known as one of the best dribblers in the world and because of age and how injury prone he has gone he has had to adapt and change the way he plays his game. For him he doesn’t get injured so easily because he wouldn’t hold the ball and run across the whole park only to be fouled and injured.
So for me I think it’s a yes; age should be a factor when determine the price tag of a player , the younger the player the higher his price and the older the player the lower his price.