Border’s answer to Amazon’s Kindle, Kobo, just dropped to $99 today.
While Kobo does support ePub and PDF natively, it’s also fully supported by Calibre, so getting your books on there should be easy.
When Barnes and Noble dropped their Nook to $150 a few months ago Amazon followed their lead that same day and dropped the kindle to $140.
I don’t think we’ll see $89 Kindles before midnight, but you never know…