I've taken silver as payment before. If it's .999 it's always worth at least spot these days. Some other coins and rounds are worth far more than spot although it's not always easy to find a person that will pay you full premium on the more valuable coins.
Eagles right now cost my about $10 over spot but if I was to sell some to a shop I'd likely only get $4 over. Your average generic round or bar is pretty easy to always get spot for as a reference.
Bb