So I am planning to buy tomorrow (garage sales) either Hammer Mk7, Railgun Mk7, Firebird Mk7 or Booster Drone. At the moment I have around 250k crystals, but I am sure I will get more beacuse I will rank soon and 2X funds. What should I buy?

A special hopper event but this time in space or space mode in MM (like TWICE said). Space mode in MM would be pretty cool and I'm looking forward for it