New Bug

I have 8 family members that I have started buying Silver for. I bought 1oz Silver Eagles in the year of their birth. The BU ASEs all varied in price depending on the Year and the 8 of them averaged $50 ea. (Spot at the time was about $30) I was thinking of doing this each year on their birthday but got to thinking; if they go to sell them someday, are they going to get close to the Premium that was paid or are they bought back at Spot or a few dollars over? Also, does the BU make a difference in Re-sale value? Thanks for an advice.