regex issue sending BAN request to Varnish server via curl
The regex seems fine.
I think you should try to escape the slashes after the first parenthesis. I assume Varnish is interpreting the expression between parenthesis as a regex (which is fine) and in a regex slashes are delimiters (some kind of special characters).
This might work:
curl -X BAN "https://oursite.com/product/(search\/home$|item\/(391|1232))"