I've wanted a set of silver mint julep cups for quite some time, but they are definitely an investment that I haven't sprung for yet. If you want the same look for less, pick up a set of silver plated julep cups. I found a few sites below that offer the silver plated variety for a very reasonable price. Use them for drinks, as vases for small centerpieces, or for a bedside floral arrangement (right now I have fresh-cut basil sitting on my counter in one of these classy cups).
4" Silver Plated Julep Cups - available at Save On Crafts for $7.40 each
4.25" Silver Plated Julep Cups - available at beau-coup for $9.25 each
3.5" Silver Plated Julep Cups - available on Amazon from Jaf Gifts for $16.25 each (free shipping)