Haha mate you are kidding yourself if you think adding a fiber-glass wide body will simply stick to your existing metal guards.
If someone has offered you 3k to fit the kit and ready for paint then take it. But dont be suprised when it hasn't been baked correctly or has even been installed correctly. Installing the kit and having it ready for paint is 90% of the work painting is nothing when looking at a wide body.
I've had my Supra in a work shop for 13 months getting this done (TRD wide body) and it has been the most painful experience of my life. I'm now having the car removed from the workshop and sent to Sydney. I would not recomend anyone in canberra...period.
Don't forget you'll need to cut your exisnting metal guards out so you can utilise the wider guard with larger rims.
If you want an honest estimate based on experience you'll be looking at over 5k and that would be cheap. Mine including kit, fitting, paint, new wheels is over the 20k mark