iknow i asked this question before but cant find it??

what should i pay for a p8 iwanting to run antilag coil pack water injection air air and pectal boost cantrol???and how much is my l8 worth as imay be getting rid of it for a p8 also is the p8 better and faster program iv been told will all that lot and the ecu £1100 is this a rip off or just what they fetch???any info pls barry