its not really a tough decision as you know you will get it all eventually  

Milltek Cat back(with the turbo back to follow) - nice feedback when driving but Id save and get the TBE rather than 2 fitting sessions
Eibach Springs and Anti-lift kit : mmmmmmm definitely
Dbilas intake with heat shield and engine cover : thats not £400 , you could do without the cover  

So thats down to 
1 :TBE milltek
2 : suspension and intake 

normally Id say suspension but theres a lot of benefit to hearing the ED30, when the std exhaust is soooo quiet.....