Well, your friends are sure trying to support your new hobby, aren't they?
But, I can sure understand your frustration. IMHO, I think you are going to have to be lovingly honest with your wife and explain that although you appreciate her thoughtfulness you would really prefer gift cards at this point. She can then pass this along to friends or not and you can graciously except the gifts as you would any gift, then either put them away until "later" or give them to Goodwill or your preference. A gift is a gift, nice thought, may work for you or not, there is no obligation.