probably the eagle morph which costed me 20k gralats.
ive bought more expensive things on Unholy Nation, but it was easier to get gralats there so I wont mention anything specifically
I thought this was about things "in general" and was about to say my laptop, but now i see it's about graal so in that case...probably the 2 player panda mount or something. (considering I can only really count purchases that happened 5-6 years ago)
I spent roughly 180k on Halloween in 2014 (didn't spend a cent, just caught hundreds of bees in snow and sold them when the witch wanted them). In terms of a single item? 75k on the black alligator mount.