You assume that lowering the price will result in the same amount of sales. In reality lowering price usually increases sales as demand and supply match again after changes. Selling 200 blades at 30BTC is more than 100 blades at 50BTC. Another point here is better ROI for buyers, as they are more likely to buy more hardware in the future if they manage to make some BTC. At current prices it's very likely some buyers may not get back their investment which will be disappointing for them and will kill the desire to buy more hardware in the future.
But you also have to consider that the more chips you sell, the more the difficulty will rise, so there are pretty strong diminishing returns in increasing sales...
With today's hashrate even hundreds of blades won't add much difficulty. It's very uncertain what other players will bring during the summer, except maybe for Avalon chips that will start hashing in July/August. But if hash rate will go to 200-300 TH/s one Blade will be a drop in the ocean. At that point they'll have to lower the price a lot, and increase sales a lot too.
