Warren Buffett is buying but he is a long-term investor and has very deep pockets so can afford to wait 20 years (by which time he will be 96). Bear in mind also that he was buying when the DOW was at 8200 but stopped when the DOW rebounded. He is also extremely good at analyzing companies to see which are undervalued, he isn't buying stuff just because it's dropped 50% he really does go through the company reports and accounts.
Personally I think the markets have a bit further to drop next week, but as you say this could be the time to be getting in, you just need to be very careful about what it is you buy.