Do any gold buyers publish their prices in terms of % of spot? If not, why not? Does it actually vary?

I'm talking about gold bullion, not jewelry. I would have thought most of these businesses have a standard % of spot price they will buy at, and would publish on their websites, but no one actually does that.

If the price they are willing to pay varies vs spot price, why?

I've never invested in gold before and am curious about how the market works.

Some good info here:

https://texags.com/forums/57/topics/3181130/last#last

Most bullion dealers/local coin shops have a range they buy at. Most of the time it stays in the 95-97% of spot. However, it depends on the market. More than half of stores don't resell to the public what they buy from someone who walks into their store. They sell to the whole seller they buy from. Since the price the whole seller will pay changes so often, it changes what the dealer will pay for yours. Most stores won't publish what they will pay because it can change quickly, especially since 2020