I would've suggested buying one from Skylynx, but his stock of upgrades has recently emptied--I bought one from him a long time ago.
The pieces themselves are excellent by the way. They fit onto the figure nicely and really give it some weight. The gun mode is HUGE!!!! In robot mode, however, the metal grips hang loosely, but snuggly in the ball joints--gotta remember to clip them into the little slots in Megatron's legs to secure them. Also, the grey tabs can clip into another little slot (on the back of each leg) too for added stillness.
Check out this listing on ebay:
http://cgi.ebay.ca/TRANSFORMERS-MAST...item1e62987162
I believe the seller is trustworthy, as he or she has been online since 2004.
