[FONT=Verdana,Arial,Tahoma,Calibri,Geneva,sans-serif]https://www.amazon.com/Ancra-40890-10-Silver-Bolt-Fitting/dp/B000I5ALW4[/FONT]
That looks like some great deals:
set of one anchor plate, snap-on ring, & mounting hardware for $15.
Set of four for $42.
Set of eight for $75.
Thanks for posting.