Where is a good place to buy the figures online?

Cause looking at places like Mercari and EBay, it would probably cost my kidney to buy even 2 figures, let alone the ones I would want🥲

The places around me that sell them only have multiple of the same Modern Sonic and Classic Sonic and if different characters show up, they’re immediately swiped up and nothing new shows up 😭

(I live in the US)