Statistics provided not only by HubSpot but other marketing solution providers and research organisations as well, suggest that inbound - if done well - is significantly more cost-effective than outbound, or at least outbound alone. Selected stats from Impact Branding & Design, SmartBug Media, as well as some of my own. Categorized by (1) Inbound versus outbound, (2) Buyer preferences and behavior, (3) The impact of content, and (4) Marketing automation.
The terms 'inbound marketing' (coined by Brian Halligan) and 'permission marketing' (coined by Seth Godin) refer to various practices that brands can apply to build positive relationships with their intended audiences, particularly on-line. The term 'content marketing' is also very closely related, although it may have a slightly stronger connotation with off-line content, like customer magazines.