The wholesale value of US junk silver coins is quoted each day in the Wall Street journal on the commodities page. Today the ask price is $14,188. This is for a bag of $1,000 face value. For smaller amounts the spread between dealer bid and ask would be pretty high.

If your friend's coins are UNC, or in some way more desirable than the usual circulated 90% silver dimes, quarters, and halves, he could probably get a bit more.

I would be willing to sell smaller quantities of junk silver for 13 x face, plus shipping if anyone is interested. Smaller is from maybe ten dollars face up to a few hundred face. I also have casino tokens that are .925 fine silver that I would sell for the value of the silver in them.