"It really bothers me that every idiot knows my shopping behaviour."
They don't. So long as the website you're buying from uses HTTPS, your connection is encrypted end-to-end with SSL/TLS. No routers along the way can decrypt the communications without your computer's private key.
The only risk is a MITM attack, but this could only be carried out by someone with access to the certificate authorities. i.e. a government. Since you said you're not a whistleblower or journalist, but just want your shopping to be private, this scenario shouldn't be too much of a concern.
