Sources: Thick vs Thin (March 14th, 2014)- Shadowless Thick vs Thin vs Does It Matter? Debate
Like most Pokmon cards, the value of Machop 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 (HSTriumphant)
Most Expensive Rare Rainbow Pokmon Cards This list ranks the top most expensive Rare Rainbow Pokmon cards based on current market prices
One Shadowless 1st edition PSA 10 Charizard, for example, sold for $369,000 in December of 2020
The Heel Turn Begins Green once again became the laughing stock when Mirrodin basically included playable (re: broken six ways to Sunday) cards for only the other four colors and the circus they had with artifacts while Green sat out in the cold in a car that wouldn't start
I put free in quotes because it is still costing you a card to do this and, a lot of times, a card is more valuable than anything else