X-link to the SF/Fantasy megathread since there's some YA-compatible Arthurian fantasy and a vintage classic YA sci-fi adventure:
Bargain @ $2.99 each from Sourcebooks (couponable @ Kobo):
- Escape to Witch Mountain by Alexander Key, the 1968 YA psychic teens novel which was the basis for the popular Disney film franchise
- 2 novels out of her Down the Long Wind trilogy of Arthurian historically-based fantasy by Gillian Bradshaw
- 3 novels in her otherworldly fey Arthurian fantasy trilogy by Anne Eliot Crompton