[Optimus Vader]

I would not suggest getting any of the giant MP Primes or Megatron. Either go iGear (I own a few myself--including PP01), or get the updated MP Prime that's a normal size. And if history repeats itself, that Prime, without it's trailer, will be a TRU or Walmart Exclusive late Summer (that's been the case the past few years).

..and since they just updated Prime to a normal size last year, I'd expect Megs to get a similar treatment eventually. That and iGear has been teasing us with their own MP Megs prototype for some time now, so that giant MP Megs is most liking getting replaced by two better versions.