Cheers. I really should've sorted all my purple walls before going to TH8, but I'm definitely getting all the purples and skulls done before going to TH9. I will have a pretty huge overlay after finishing my buildings while I finish all my research and find all the dark elixir to get my BK up to level 10, but if I save enough gems to boost barracks, I'll be able to mine the approx. 100mil gold to get all the skulls in time.
It really is expensive for walls. I dread to think what it'll be when the TH11 update eventually comes out! 16million for one wall piece?