We do not offer “off the shelf” aero kits simply because we can alter these in so many different ways for specific client needs that it is not feasible to have them in inventory. However, we can build an assembly SPECIFICALLY for your car. The cost will vary depending on final design, but a PROPERLY DESIGNED and setup rear diffuser will typically cost $850-$1500 INSTALLED Please email us at : SimtecMotorsports@yahoo.com for consult and for shipping charges