Guesstimation on rust fixing

[LizardKing]

Can someone do a rough guess on how much the following 2 patch's of rust might cost to fix?
This one is pretty much all the way through on this and will need either new metal putting in or fibre glass.

This one is hard to tell but looks/feels like its all the way through as well. I,ve pulled away part of the rubber surrounding and it goes all the way back

Thanks!

 

[LizardKing]

Thanks,
yep its a 4th gen Honda prelude with the statuary rusty arches

I'm worried though if i started attacking it with a grinder i/it would come off a lot worse, I'm not afraid of getting my hands dirty on the mechanicle side of things etc, but im about as good as a 5yr old when it comes to paints.

 

[LizardKing]

I cant imagine white being a hard colour to match

If the weather holds out for a few days i may attach it with a file, see how far back the actual rust goes, may leave a big gap in the arch but it will be rust free!!