I just googled, and by the way when you want to google for something with qustionable legality, it's best to use search engines not based in western countries, such as Yandex. There ended up being a lot of sites advertising the solutions manual for sale. But also, there are entire subreddits where these people post threads advertising that they have whatever ebook/solutions for sale with a whatsapp phone number included in the content. I messaged on Whatsapp and sent a paypal payment (yes, I had no recourse, it was a leap of faith) but it's not that much a risk since it's only $25.