Right now the largest BTC purchases are miners buying asic chips through Avalon and BFL. If you add up the revenue for avalon just with batch 3 and the 10,000 chip orders, avalon at last check has received 100,000 BTCs. Now what does avalon do with these coins? A large number need to be converted to fiat to pay for production costs. Let's say only 50% of coins needs to be sold to make enough fiat profit to order the chips. That is still 50,000 coins. Or $5000000 leaving the BTC "realm."
If one sold 50,000 coins at once it would push mtgox down to 80. I'm sure avalon doesnt use that, but both big dips happened after batch 3 sold and after the 10,000 order sets sold...
While correlation doesn't equal causation, you are correct in that one would be a complete fool to ignore the fact that a huge amount of coin has moved through the hands of BitSyncom et al. His network of college friends and others working with xiangfu and ngzhang definitely need paid.
Smart money would say that they'd work with an exchange to accumulate funds on behalf of that exchange, which would then sell existing coin they hold in anticipation of receiving coin from the
50k address for the chip orders at a later date. That address might not even be owned/run by the Avalon team, it could just be where the payments are going for the transaction processor, who will only start to tap into those funds when their present funds have been sold/spent via whatever algorithm their bots are trading at.