Though more common today, older reverse holos steadily gain value over time
To find out the price as close to reality as possible, you can find a good site and put it up for auction
Or you maybe just wants to deal 20+80 damage with Joltik's and Elelktross two damaging attacks- and then attach 2 guaranteed Energy cards to Eelektross, or you maybe want to first Absorb some Energy with Eelektrik's Zapcharge and then send then back to your other Pokmon with its second attack
This made thematic sense because each of the three sets was centered around and named after one of the three categories of Pokmon V: Pokmon V, Pokmon VMAX, and Pokmon VSTAR
Though it does not count itself, the mana from the green side is scary good that I can't unsee the improved mana capability compared to Reserved List land, Gaea's Cradle
Chart shows the price of Excalibur, Sword of Eden #169 at the end of each month going back as long as we have tracked the item.