build this last week from 0.5mm aluminum, if you're offroading you might what to use thicker aluminum, but if you fold the edges it'll be much more rigid then the basic sheet will let you believe.
a 100x50mm sheet was 13€ thicker sheets where about 30€
the whole project costed me maybe 20€ or so
(depending on your buget that leaves quite some room for improveing meterial quality)
i used matal sheers to cut small bits of and folded the sheet over a table edge and over metal bars, and some aluminum profiles for support.
most of these skidplats commertially available are expensive because they include labour cost, profit margin and shipping.
if you can spare a couple of hours you can build something with the same specs and functionaliy (or better) for a fraction of the price.
mine was build for pure aero with a minimal weight, so heavy impacts might dent it (but its inline with the subframe so if it hits something my bumpers most likely ripped of as well)
there's 3 screws in the subframe at the back, but i could have worked around that if they're gone all attachements are withing reach from above trough the hood.
so you might look into a light removable aero pan you can pop of in 5 minutes when you're driveing fast in the dirt