I've had that happen from other companies too. I won't order if they don't have an amount of seed for the price listed. It makes me furious.

Did you order them from burpee.com, or are these from a store rack? If you bought them from a store rack, especially the ones they supply to WalMart, it would not surprise me. Impatiens seed is expensive anyway, so if they sell the packets for WalMart prices, something has to give, in this case, seed counts.
Last year I bought Neon Lights chard (Burpee exclusive) from WalMart and from one of the home improvement stores, the WM seeds were priced at $1 and the home improvement store seeds were priced at $1.79. But the WM packet only had slightly more than half as many seeds.