It seems the European wave of Marvel Cinematic Universe Marvel Legends, complete with Hulkbuster Build-a-Figure, is now showing up in TK Maxx stores.
The wave, packed exclusively for the European Market, is made up of 7 MCU figures and buying the full wave will allow you to build the huge Hulkbuster figure. And not only that, the Hulkbuster is presented in more desireable darker red gloss plastic than the original worldwide release.
The figures are £12.99 each in TK Maxx, but don't expect to find the full set. The business model for TK Maxx is to split the cases and send in individual figures to stores. That means you will need to do some hunting. Don't forget to also try Homesense stores - which are part of the same group.
