To the OP: I also purchased this at $10, thank you!
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I did a search for coupon codes and I found the exact coupon code from [1].
Can I ask, what would the problem be if the code was affiliated with an affiliate promotion?
The end user pays $10, which I think we can both agree on. It's a "NET" benefit for HN users to learn something new very cheaply.
If couponkoo negotiated with the vendor of the product, so that they can advertise a coupon and get some kick back, you know because they too have to keep the lights on.
Is that such a big deal now on HN? Can you please explain yourself because I don't see an issue here personally!