The purchase is ~3 months old, but i will just try it.

I bought the GBH TC for 1400 Keys + DF Robo Stove + Aurora Pithy.

https://imgur.com/a/ftlE1Kv

https://backpack.tf/item/1775475483

DF Robo Stove sale:

https://backpack.tf/suggestion/69a22fb88f446a44d5036d16 (~680)

For the Pithy i've found 1 pure sale:

https://backpack.tf/profiles/76561198029127660#!/compare/1766880000/1767052800 (302 Keys)

Looks like all others are bulk sales and can't be priced. Also the there's 1 seller @320 Keys and 1 buyer @270 Keys. I guess taking the Pithy @302 should be fine.

1400 + 680 + 302 = 2382, rounding to 2400.