The law -- according to my research and my accountant is as follows:

Sales Tax must be collected by CA Based Seller (ONLY on sales within the State of CA to CA Buyers), with the following exception:
Sales of Numismatic or Bullion items are exempt if the sale is greater than or equal to $1,000.

For those bidders who live in CA and purchase either 1 item of $1K+ from me on a given day -- or multiple items that add up to $1K, I can reverse out the tax on the invoice.

As for the 1 Oz. vs less than 1 Oz. issue, I have never come across it. If anyone knows of an official site from the State of CA addressing it as some sort of alternate Exemption, I would happily look it up and apply it if legal.

Thanks

Dave W.