Basic kit that you need:
The Ion: £90-150 depending on condition and upgrades but average is £100
Hopper: I am getting an Egg they are fast enough for it and only like £25-£30
Air: Make sure you run it off air, I am getting a 1.1ltr 4500psi but it depends on how much your going to sue it and for how long. Thats about £60 air bottles have a "born date" then they last 15 years and need to be tested evey 5.