Here's a breakdown of the best selling cards in December and the sets they were pulled out of! 

Based from TCGplayer

 

 

  GENGAR VMAX- FUSION STRIKE

UP 25%

$413 TO $515

 

CHARIZARD EX SIR- PALDEAN FATES

UP 15%

$137 TO $158

 

GIRATINA V- LOST ORIGIN

UP 3%

$395 TO $409

 

 

HYDREIGON EX SIR

UP 40%

$100 TO $140

 

EEVEE SIR - TWILIGHT MASQUERADE

UP 8%

$62 TO $67

 

CHARIZARD EX SIR - OBSIDIAN FLAMES

UP 41%

$61 TO $86

 

MEW EX SIR - PALDEAN FATES

UP 8%

$179 TO $193

 

BULBASAUR IR - STELLAR CROWN

UP 25%

$40 TO $50

 

CHARIZARD EX SIR - 151 ENGLISH

UP 11%

$179 TO $199

 

LUGIA V ALT. ART - SILVER TEMPEST

UP 9%

$206 TO $225