80 ounces of silver is worth more than 100 common strikes. You are asking to trade 60 ounces of silver for 80 ounces of silver. If you have rare ones in the mix, that may help even it out. An ounce of silver on eBay will easily bring $18 to more than $30 per ounce. You are lucky if you get $14 for a common nowadays, usually it's $11 to $12 before fees....