Travertine Floor Restoration

I have approx. 500 of travetine marble installed in family room. The
tiles appear to have streaks on the surface as if the grout was not
properly removed when installed. I have tried several grout removal
products with no satisfaction. Recently a person showed me that using
200 and 400 grit compound, applied wet with a floor polisher would
produce a satin finish on the travertine which hid or removed these
streaks.
a. Do you have any other suggestions?
b. Do you sell or can you refer me to someone who sells the grit. I live
in northern California, zip 94513. If possible, would appreciate an
estimate of that the material would cost me delivered.

Thanks,
Mort Morgenstern.