With more than 1,000 items for sale, the Isabella Stewart Gardner Museum’s new gift shop will offer a wide range: everything from $6.50 hand-drawn note cards to a $70 gold-plated bunny and a $500 sterling silver cuff engraved with a quote from Marcel Proust (“Let us be grateful to the people who make us happy; They are the charming gardeners that make our souls blossom.’’).