I believe the last price cut (which was also very significant) was before that date, so you still got a very discounted player. That was also way after the EOL announcement, at which point most people realised (and discussed here) that purchasing was a gamble between the product selling out, or the price dropping further.
SB do have a price guarantee, but it is only for 30 days (which is not uncommon).
Sorry you feel you lost out, but all any purchaser can do is decide how much something is worth to them at that point in time. I must admit I was a little taken aback by this reduction, but clearly it is a final push to move the remaining stock off the shelves.
Rob