HubSpot's Slack integration allows you to turn Slack messages into a HubSpot task or ticket.

You will be able to receive notifications exactly when the prospect opens the document with prices that you emailed him earlier, and use this perfect moment to call him and complete the deal.

You will be responding to inbox chats in Slack - or you can click Reply in Inbox and go to the chat in HubSpot - but either way, the entire conversation will be logged in your inbox in real time.