If you keep buying the USB miners at that ridiculous price, they have no incentive to lower the price. The only thing this USB miner will do for Bitcoin is to add more of them to ASICMINER's coffers.
See, ASICMINER can't deploy too much extra hashpower yet until Avalon/BFL ship more of their units since they'd be nearing hashrates with which they could conceivably execute double spends. Even the threat of that possibility should be enough to deter them since that would most likely erode confidence in BTC.
Totally agree, but being involved in R&D and product development, I know how much effort goes into shipping the first production batch.
Given I don't think USB miners are going to be competitive in the long run, I would like to see all bugs ironed out now so with dwindling demand it will still be cost effective to produce the product at a lower price as opposed to pulling the product before it is fully developed because of lack of demand.
However your scenario is likely should the demand stay high without competition.