For a deep dive into this card's value and rising price, here's a handy video from Pokmon YouTuber PTCGRadio: The basic gist is this - these promos were only available to fans who pre-ordered the Mew Ultra-Premium Collection from the Pokmon Center site
X were retired at the end of the Platinum era of the Trading Card Game, to be replaced in HeartGold & SoulSilver by both Pokmon Prime and Pokmon LEGEND
2 Bello, Bard Of The Brambles The Commander Has Come Out To Play With a deck filled with tons of unique cards, Bello, Bard of the Brambles still stands out
That cements this card as the top 5-color elemental commander
July 30August 2: Gen Con at Indianapolis, Indiana, USA July 30 : Release of Mystery Booster: Commander Edition August 59: STLV: Trek To Vegas convention
Third, see if you can find lands that cover more than one of your colors (especially if they can enter untapped)