where can i find official tandemaus & maushold pokémon cards?

hi! im looking for tandemaus and maushold cards and would like some advice if anyone can give it!

my girlfriend recently has been really interested in pokemon and also has a birthday coming up :).

i have plannss! big plans!

first off, their favourite pokemon are tandemaus & maushold. so i want to buy them all tandemaus/maushold cards that exist (and that i can afford). i just want them to have real cards. they only have a few so far so really starting their collection with all of their favourite cards would be so amazing.

if possible, i need to find a place that i can buy them second hand with more trust that theyre official, at a good price, and preferably in bundles to minimise spending so i can get them other stuff too. but i also know you cant be too picky somtimes.

for those curious, im also planning on finding a meowth binder for them (they also love meowth) and some packs from the store. im really excited but dont want to mess anything up.

any help on where to shop/how to spot fakes would be so so helpful. thank you :)