Stumbled on an excellent webpage for the Cundi mantra today while answering a question for the Omniglot blog. Lots of background info and links to other info.
Cundi is a form of Avalokiteśvara. The Cundi site thinks she may be a Buddhist form of the goddess Caṇḍī, a non-vedic tribal goddess from Bengal. There are other non-vedic goddesses as well particularly (Pāli) Siri, (Sanskrit) Śrī, who becomes Lakṣmī - a goddess of luck.