Legacy by Susan Kay is an excellent historical about Queen Elizabeth I of England and one I've wanted to own for years (it was severely out of print for some time and the library got rid of their old copy). I just bought it during the St. Patrick's Day sale @ OmniLit/All Romance eBooks. NB: nostalgia may be blurring my recollection of how good it is, so sampling is advised.
If you like quasi-
Mists of Avalon-esque Arthurian fantasy,
Merlin's Harp by Anne Elliot Crompton is not bad for the price. It was a former freebie in 2010, so I'd check the archives, but my
impressions of it are here if you don't already have it and the premise sounds interesting.
Also in the same subgenre, Persia Woolley's
Child of the Northern Spring is supposed to be a good Arthurian fantasy centred around Guinevere (and another former freebie) but I haven't gotten around to reading it. But at 99 cents it's a definite bargain if you like the sample.
All of these are on month-long promo sale from publisher Sourcebooks and should be the same prices in other stores if people want to get them there.
If you are looking to try the Iliad, the Richard Lattimore translation is said to be a good one (haven't read it myself) and is fairly cheap at $1.99.
And the $2.99 Kurt Vonnegut and Aldous Huxley books are sfnal classics if you like speculative fiction. Rosetta Books are sometimes offered at the same prices elsewhere (and they're discountable with Kobo coupons, so may work out cheaper that way for non-Kindlers). Richard Matheson's
I Am Legend, also out from Rosetta and recommended upthread is also very good. I have a French translation somewhere which I really ought to get around to reading and comparing at some point.