Love 'em or hate 'em, one thing's for sure -- e-readers just keep getting cheaper. The latest to see a dip in price is the Sony Reader WiFi
, which debuted at $149.99 just a couple of months back, but has now received a permanent drop to $129.99. What's more, Sony is also running a trade-in program through the end of December that will give you an additional $50 off if you turn in any old e-reader. Not quite the instant discount that an ad-supported Kindle gives you, but certainly not a bad deal if you're looking to upgrade from an older model.