It varies. I have sent literally handfuls of bonus coins to other GIN winners in the past. A silver war nickel or two may show up, but the bonus coins are not going to have a higher price than the auction coin. It's a bonus. With that said though, higher auctions and repeat customers generally find better bonuses.
This GIN will receive at least one silver war nickel among the bonus coins. I still think they are great bonus items though. The opportunity to relist them for points or keep them for your own collection exists.
This auction will most likely receive 2-3 bonus coins for GIN.