There has always only been two options for the 4850x2. Sapphire is the only company that makes them, and they have two versions, a 1GB (512MB per GPU) and a 2GB (1GB per GPU). You must've been looking at a different card a couple weeks ago.
ATI's card partners are apparently resisting the price cuts because they don't want to hurt their margins, and ATI's cards are already price-competitive with nVidia at their current prices. Still, you can find a 4850 for as low as $120 after MIR and a 4870 for as low as $155 after MIR on Newegg. IIRC, ATI's "price drop" was going to be done with MIR's, so it looks like at least a couple of their partners are cooperating with it, but it doesn't look like Sapphire is one of them.