Games of Deception is also my biggest purchase, but that's 5 toys. When I buy box sets or bundles, I distribute the cost of the bundle to the included toys based on the ratio of their size class prices (not their perceived value). So, my top 10 are:

1. $269 Botcon Dreadwind
2. $183 MP Grimlock
3. $179 MP 4 Convoy
4. $161 Botcon Dirge, Thrust, Thundercracker and Bug Bite (each)
8. $147 Crystal Convoy
9. $133 Henkei Wildrider
10.$132 Botcon Alpha Trion