Another New Aquarium Question

Once I settle on an aquarium, I'd like to add some Shale and Lava rocks
from our local area to create a nice looking setting and to provide some
'hiding' space for any fish wanting to do so. I know that this not
recommended due to possible contamination issues. HOWEVER - if these
items were soaked in say a 5% or 10% solution of bleach, then thoroughly
soaked & rinsed, would they likely be OK from contaminates and perhaps
minerals(?), or should I simply bite the bullet and pay a heavy price
for features from my local fish store? I'll use whatever gravel comes
with the set up and would really like to make it look nice inside,
however the safety of my little finned friends is more important than
the use of local rocks.

Thoughts, comments, absolutes?

Grandpa John