Kelvin, I have no idea on cost (as I've done mine with my dads help), but it may be worse than it looks. I would get the green sound deadening off in that area. Heat gun and a scrapper. Then you can see how bad the top layer is (as rust hides under the hideous green stuff - I would recommend getting it all off). The other issue is that there are 3 layers of steel in the foot well front, so it will depend on how its put back. Thicker plate of less layers or 3 layers original (which also depends on how far the rust is).
No help but it might be more work than first glance. Removing the green stuff will reduce the cost (as this can take a while).
My final concern is that the curved section on the left looks very orange.....and may also need a plate. Both areas on my white LX had this.