Check out Underground Racing's website. I think they list prices for their upgrades. Would you consider the Gallardo?
Edit: For Stage 1, it's $39,000 for both the Gallardo and R8. With 93 octane, you get 700 HP on both cars. With 117 octane, it's 850 WHP with the Gallardo and 1000 with the R8.
PSS10 Coilovers | TMS Camber Plates | LED Tail Lights | SuperSprint Race Exhaust | E60 Shift Lever | ZHP Steering Rack | GroupN Motor Mounts | RE Trans Mounts | AKG 90A Subframe Bushings | AKG 95A Diff Bushings | AKG 90A RTABs | TMS Subframe Reinforcement Plates Epoxied | Euro Tune | Schroth Quick Fit Pro | PFC 08 Pads | CPI Stepped Headers | Motul RBF600 | Rear Seat Delete | Centric Slotted Rotors | SAP Delete | UUC Clutch & Brake Pedal Bushings |