Refurbished units of both the Kindle Fire ($169) and Kindle Keyboard 3G ($129.99) are back in stock at Amazon (but I don't expect them to last for long). These units are usually impossible to tell from brand new (although the Keyboard unit often doesn't ship with the wall charger, buy you can pick one up for under $10 or just charge via your computer) and come with the same warranty from Amazon. You generally can't get the Amazon extended warranty on their refurbished units, but Square Trade has traditionally let you get them thru them (although I generally recommend against getting them on items like these that are relatively inexpensive and often end up getting replaced by newer technology after a couple of years).
In general, seeing a listing for refurbished units happens a bit more often if a product is getting ready to be dropped by Amazon (something I expect with the Keyboard unit, eventually, which is a shame as it is MUCH better than the two later models); with the Kindle Fire, they likely have had a number of returns by those who decided they preferred eInk; there are now persistent rumors of a larger Fire this fall, but I don't think the smaller unit will be entirely replaced (although I could be mistaken).
