Well, MP 01 if you go for the Hasbro version would be a bit cheaper I believe although it's got neutered smokestacks.
You don't want to get the MP 10 instead and prolly wait if HasTak will develop a size equal MP megs (albeit prolly not a gun - mebbe G2 version)?
If not Id say get what is easily available so you don't miss out and have to pay by the nose later on - Acid Storm or any of the available seekers.
Not interested in Sideswipe?
Wanted AM partner Vanguard, Myclones Dirge, G1 Victory Leo, e-hobby Dark scream ( the black version), e-hobby Magnificus
Parts- AM partner Basher-side guns, G1 Actionmaster Elite Windmill's blades[I][B]