Like most Pokmon cards, the value of Gengar ex depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Temporal Forces)
At this point in the game, the only other opponent you'd be able to defeat would be Weevil, whose forest creatures are weakened by Wasteland terrain
Commune with Beavers is playable, but its very easily cuttable and probably not something you ever want to prioritize
It's unwise to put too much emphasis on week-one success with any archetype, but the Towns deck has been really fun and done quite well in my testing
If it gets out, the advantage it will offer you is off the charts
Though, if youre looking for a perfect PSA 10 grade card, you can buy a Base Set 2 Venusaur for roughly $815