It is absolutely perfect time to buy one.
It has been for quite a few years.
And since Sony PRS-500 came out almost 3 years ago it is perpetually high time to buy one. I still use my PRS-500 daily and despite the fact it uses the oldest e-ink screen in existence it is more than adequate for reading fiction.
There *are* some models just around the corner. Guess what happens when Kindle DX comes out and that new 5 inch models from Hanlin and Netronix are ready for preorder?
I tell you what happens. Another company will have announced new breakthrough model at that time. Or Bookeen will have announced that the new firmware with Folder support is being made available Real Soon Now (TM)
When you buy a new gadget, you HAVE to accept the fact that your sparkling new toy is obsolete the next day. Otherwise you will never buy computer.