Again, the beloved EBAY! Do a search for both 'Fireworks Dept 56' and 'fireworks village' ...if there are any out there for auction, they'll show up. I have 2 sets (each set has 3 prongs of green wire with its end being the firework plume), fairly inexpensive, both sets delivered $27 incl. insurance. Not bad since they must've been $15 or so new at the Dept 56 store.
Just took a peak on eBAY and there's a set up for bid, item# 280150853268! There you are!