The ZEX Kit is approximately $660.00. The tuner is $300.00 to $600.00 depending on the type. The best tuner is the Diablo. The Diablo has two different tuner depending on your budget. And they both do the same thing.
The ZEX Kit....This is the one I used for my LS1.
Diablo Trinity Tuner
Diablo Intune
If you just want to use it for just the Nitrous the Intune works just fine.
Within the LS family DO NOT use Nitrous on the LS9