If you can, try to hunt down some of
Richard Matheson's short stories. A lot of them were adapted into some of the better classic Twilight Zone episodes and can be very eerie in tone without the slightest bit of gore.
In that vein,
Rod Serling also did prose adaptations of his own generally excellent TZ episodes, which you may be able to find cheaply in the used bookstore. Or just borrow a copy of the DVD release and watch away.
And
Charles Beaumont, a contemporary of both who also wrote some of the better TZ-original and adapted stories, has one of them up on Project Gutenberg, and has been described by Dean Koontz as an "influence" according to the Wikipedia article, though I don't know if that endorsement will push you towards or farther away from his works.
Both
Ray Bradbury and
Harlan Ellison, while not horror/suspense writers per se, have written a number of genuinely creepy and frisson-provoking short stories.
One of Bradbury's classic novels which shouldn't be hard to find is
Something Wicked This Way Comes. I can't seem to recall or find the title of the story with the horrible thing lurking in the attic, or the one with the thing that ate people's bones but left the rest of them intact, but
The October Country is an anthology of his scarier stories that was reprinted in 1999, so you may be able to find it in a library.
Ellison is a decidedly more SFnal writer, so that may not be to your taste, but his creepy classics include
I Have No Mouth And I Must Scream, and
A Boy and His Dog.
If you want e-reader friendly formats, classic Ellison, at least is available DRM-free via Fictionwise and Baen's Webscriptions. Bradbury, unfortunately, has decided not to let his works be released in e-format. Matheson is available in both novels and collections in the Kindle store and likely elsewhere. Beaumont will be another used bookstore/library search, though he's had stuff reprinted within the past couple of decades, which should help a bit.
As for some classic scary tales available via Project Gutenberg et al.,
Ambrose Bierce has written a couple (
An Occurence at Owl Creek Bridge being probably the most famous, and another Twilight Zone adaptation), as has English
M.R. James (gets adapted for BBC Radio every so often).
And I've always liked
Edgar Allan Poe and
Bram Stoker, whose non-Dracula works you can find free online at
BramStoker.org, and am currently partway through the B&N Classics editions of
Mary Shelley's Frankenstein and
Robert Louis Stevenson's Jekyll & Hyde, both of which I find considerably enhanced by the annotations, particularly the stuff relating J&H to the Jack the Ripper frenzy going on at the time.