FTDI is based in scotland, & the USD/GBP has been doing steadily 2/1 for the last half year.
in general, however, prices do not perfectly track exchange rates. that includes my shop as well.
If they're made in Indonesia, it could explain the price hike, if the US dollar is dropping compared to their currency. Even if the office is in the UK, their manufacturing costs would be rising in pounds or dollars.
I know it doesn't track exactly, which could explain why it's held steady for so long and then had to shoot up suddenly.
I noticed that it includes your shop, ladyada, which is one reason I bought mine from you. I'm just sorry I didn't get a motor shield and maybe a second protoshield while I was paying the shipping anyway. I did notice the Arduino went up 50 cents right before I ordered, but considering what the currency market is doing, I'm not complaining.