Customer portal alternative method

I had checked it out and there’s many more I’d like the Client to do that the portal doesn’t allow. Add products, view sales orders, upload documents, create accounts and contacts, etc. And at $500 per month, it doesn’t make sense for us. We operate an IT company and we’ve taken the opensource router but at the price we could just sign up with a PSA or some other paid software for much less. Not to mention the additional costs for adding the features we need in it. That’s why we took the route of adding the clients as users.