It's quite a costly endeavor once you get going.
One thing to note is that you'll need the following movement types and elemental types to access every area:
Climb
Rocket
Speed
Spin
Bounce
Teleport
Dig
Sneak
Magic
Wind
Earth
Fire
Undead
Tech
Water
Life
Edit: These are the characters I bought to get those combinations most efficiently:
Blast Zone (included in bundle)
Wash Buckler (included in bundle)
Rattle Shake
Magna Charge
Free Ranger
Hoot Loop
Stink Bomb
Rubble Rouser
With those six character (plus the two that come with the bundle) you should have one of each of the eight elemental types and one of each of the eight movement types.










