Most you've spent on a Single figure?

[EpicRaptorMan]

I spent 39.99 on a Malaysian Tapir by Schleich once (14615).
After shipping and tax it was just a hair over $50. 

Now Schleich decides to make another model to be released in 2022!

[bmathison1972]

I don't remember my most expensive, but I think I've dropped $100 or more several before. A couple of the Kaiyodo Revogeo figures may have been 100-120, and my Merial tick pair I think was 100 USD.

[GojiraGuy1954]

probably Rebor's V-rex

[stargatedalek]

SH Monster Arts Rathalos and KanColle Nagato Figma, both around ~$200. After that probably Girls Frontline UMP9 Figma and Bring Arts Chocobo at around $150. The Revogeo Red-clawed crab and Giant waterbug, and Mattel super colossal dinosaurs all come close at around $80-$100 each.

[BlueKrono]

I bought a bronze snapping turtle this year for $150 + $50 shipping. If we're talking prehistoric though, triple that. And if we're talking Lord of the Rings statue... double THAT.