Have you considered changing to instabill.com/blog ? This would then concentrate the link value to the main domain name (blog.instabill.com is a sub-domain and therefore considered almost like a separate domain).
Whichever you choose you need to make sure that every single page on the current blog is 301'd to the new page on the new domain.
If you do choose to set up a new domain-name then in addition to the 301's you can also register a change of site name in webmaster central.
I would personally advise considering the instabill.com/blog route. What blogging platform are you using ?