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I want to get the SuttaNipata from Wisdom Publications for its extensive commentary, and I might eventually purchase a hardcopy of the Visuddhimagga.
‘Beyond the Tipiṭaka: A Field Guide to Post-canonical Pāḷi Literature’ was originally published on Access to Insight in 2002, and updated and republished in 2016 on ancient-buddhist-texts.net. The Wiki on Atthakatha (Pali for commentary) covers similar information.
sirimangalo.org has a large collection of pdfs—including all four parts of ‘Buddhist Stories from the Dhammapada Commentary’—tucked away on their pdf page. Many of the translations are quite old.
Ven. Dhammavuddho Thero has a series of video discourses on the Nikayas on YouTube with additional resources on vbgnet.org.
I recall Ven. Henepola Gunaratana giving many talks on the suttas about 10 years ago, but I can’t find where I originally heard them. Trekmentor and bhavana.us appear to have mirrors.