Show median prices, or add option to switch between median and average price

Average price works perfectly fine for most titles. But for rare games that get fewer sales each month-- e.x. boxed NES games, Neo Geo, TurboGrafx, certain SNES rpgs -- the sample size is so small that average isn't statistically valuable at that point since it could be influenced by one or two sales. Median isn't as susceptible to being skewed by extreme variations in price, so it would minimize the impact of those few outliers that sold for notably lower or higher than average.