There’s currently a bundle of Dynamite comics over at Groupees. You get 100 comics when you pay $10, but there’s also $1 and $5 tiers. They’re available in PDF, ePub, and CBZ formats. You can choose to donate 20% to the Comic Book Legal Defense Fund, and there are some interesting rewards for the top five contributors.
Top contributor:
Top Contributor illustrated on the cover of an upcoming Dynamite comic book, alongside the title character, and the cover will be drawn by superstar artist Jae Lee. The winner will also receive 100 copies of the comic and the original artwork
And for #2-5:
Contributor will be illustrated as characters on one interior page of a Dynamite comic book
The Dynamite bundles started with Humble Bundle, if I recall correctly. I frequent both HB and Groupees and am sure the former had a few good comics bundles features as part of their regular Books Bundle.