Help Please

[buggs8463]

Am buyin a Suzuki GSXR 400 but the think is its icu or cdi these are the same thing i think. Its the box under the tail light that has burnt out now is it just a case of buyin a new one and putting it in or is it more complercated than that please somebody help i do have a pic i will attatch it to the thread. oh i asked the guy would it not start and he said no. I seen some cdi boxs on the net priced around 90 pound am hopin they are the ones or am on the right track. Am buyin the bike for 500 pound.