I've recently begun reading up on the Avataṃsaka Sutra and was curious if anyone here is aware of any available Sanskrit text. Thank you.
I think it is only complete in Chinese & Tibetan, the Chinese being much longer than the Tibetan. Sanskritic manuscripts are too fragmentary to form a full Buddhāvataṃsakasūtra.
This is a particular section of the Buddhāvataṃsaka that we happen to still have legible manuscripts for: http://www.dsbcproject.org/canon-text/book/40. It is called the Gaṇḍavyūhasūtra, you can read the Chinese correspondence at T279.319a6 in the Taishō Canon 入法界品 Dharmadhātupraveśanaparivartaḥ Ch 39 in Thomas Cleary's English translation "Flower Ornament Scripture" it is called the "Entry into the Realm of Reality" chapter, at page 1135: https://archive.org/stream/TheFlowerOrnamentScriptureATranslationOfTheAvatamsakaSutraByThomasClearypdfdtyxxytd/The%20Flower%20Ornament%20Scripture%20A%20Translation%20of%20the%20Avatamsaka%20Sutra%20by%20Thomas%20Cleary%20%5Bpdf%5D%20%7Bdtyxxytd%7D#page/n5/mode/2up.
You should be able to find it in the Digital Sanskrit Buddhist Canon. Unfortunately I don't have a Sanskrit IME to give you the direct link to the text, but doing a search should bring it up.