If they're going to be worth more for their silver content than the grade of the coin, I'd just put it aside in a silver pile and list all of the silver at once.
The rest will probably still sell, even if it's just at 99p, but you'll definitely get your money's worth for the silver. Don't forget to list what you have, so weigh all the .500 silver and write down the weight, then the .900 etc. So the listing says, for example, you've got 50 grams of silver which breaks down as 20g @ .500 and 30g @ .900.
Take a look at a few bulk listings on eBay and get a feel, what would you be more likely to bid on, a listing of a pile of silver coins that just says 'silver coins', or one that tells you exactly what you're getting in terms of weight and silver content.