I also recommend blendle. It has the most reasonable payment system.
btw, I've purchased a few articles from Der Spiegel but they were around 0,75€.
I've been waiting for these guys to launch in the USA since I first heard of them. They're still in beta?
I've been using them in the US for over a year for what that's worth.
I'm using https://blendle.com, which offers a wide variety of publications with payment per article (usually something around 0.70 EUR, with the odd 1.99 EUR for articles from DER SPIEGEL). They also have a daily mix of manually curated content and content based on the articles I purchased in the past, which works really well. I'm afraid it's only available in the Netherlands and Germany so far.
I didn't know the Brave browser had a payment model built in, will give this a try as well.